The access to internal tables can be optimized by using the appropriate table type and specifying the table key.
The table key is a set of fields that uniquely identifies a row in the table and determines the sorting order of the table. The table key can be either the primary key or a secondary key. The primary key is defined by the table type and the table definition, while the secondary key is defined by the user using the KEY statement1.
The following results in faster access to internal tables:
* B. In a sorted internal table, specifying the primary key completely. A sorted internal table is a table type that maintains a predefined sorting order, which is defined by the primary key in the table definition. The primary key can be either unique or non-unique. A sorted internal table can be accessed using the primary key or the table index. The access using the primary key is faster than the access using the table index, because the system can use a binary search algorithm to find the row. However, the primary key must be specified completely, meaning that all the fields of the primary key must be given in the correct order and without gaps2.
* D. In a hashed internal table, specifying the primary key partially from the left without gaps. A hashed internal table is a table type that does not have a predefined sorting order, but uses a hash algorithm to store and access the rows. The primary key of a hashed internal table must be unique and cannot be changed. A hashed internal table can only be accessed using the primary key, not the table index. The access using the primary key is very fast, because the system can directly calculate the position of the row using the hash algorithm. The primary key can be specified partially from the left without gaps, meaning that some of the fields of the primary key can be omitted, as long as they are the rightmost fields and there are no gaps between the specified fields.
* E. In a hashed internal table, specifying the primary key completely. A hashed internal table is a table type that does not have a predefined sorting order, but uses a hash algorithm to store and access the rows. The primary key of a hashed internal table must be unique and cannot be changed. A hashed internal table can only be accessed using the primary key, not the table index. The access using the primary key is very fast, because the system can directly calculate the position of the row using the hash algorithm. The primary key can be specified completely, meaning that all the fields of the primary key must be given in the correct order.
The following do not result in faster access to internal tables, because:
* A. In a sorted internal table, specifying the primary key partially from the left without gaps. A sorted internal table is a table type that maintains a predefined sorting order, which is defined by the primary key in the table definition. The primary key can be either unique or non-unique. A sorted internal table can be accessed using the primary key or the table index. The access using the primary key is faster than the access using the table index, because the system can use a binary search algorithm to find the row.
However, the primary key must be specified completely, meaning that all the fields of the primary key must be given in the correct order and without gaps. If the primary key is specified partially from the left without gaps, the system cannot use the binary search algorithm and has to perform a linear search, which is slower2.
* C. In a standard internal table, specifying the primary key partially from the left without gaps. A standard internal table is a table type that does not have a predefined sorting order, but uses a sequential storage and access of the rows. The primary key of a standard internal table is the standard key, which consists of all the fields of the table row in the order in which they are defined. A standard internal table can be accessed using the primary key or the table index. The access using the primary key is slower than the access using the table index, because the system has to perform a linear search to find the row.
The primary key can be specified partially from the left without gaps, but this does not improve the access speed, because the system still has to perform a linear search.
References: 1: Internal Tables - Overview - ABAP Keyword Documentation 2: Sorted Tables - ABAP Keyword Documentation : Hashed Tables - ABAP Keyword Documentation : Standard Tables - ABAP Keyword Documentation

The correct ON condition that must be inserted in place of "???" is:
ON Sprojection.carrier_id=Z_Source2.carrier_id
This ON condition specifies the join condition between the CDS view Sprojection and the database table Z_Source2. The join condition is based on the field carrier_id, which is the primary key of both the CDS view and the database table. The ON condition ensures that only the records that have the same value for the carrier_id field are joined together1.
The other options are not valid ON conditions, because:
* A. ON Z_Sourcel.camer_id = 7_Source2 carrier_id is not valid because Z_Sourcel and 7_Source2 are not valid data sources in the given code. There is no CDS view or database table named Z_Sourcel or
7_Source2. The correct names are Z_Source1 and Z_Source2. Moreover, the field camer_id is not a valid field in the given code. There is no field named camer_id in any of the data sources. The correct name is carrier_id.
* B. ON Sprojection Camer=Source2 carrier_id is not valid because Sprojection and Source2 are not valid data sources in the given code. There is no CDS view or database table named Sprojection or Source2.
The correct names are Sprojection and Z_Source2. Moreover, the field Camer is not a valid field in the given code. There is no field named Camer in any of the data sources. The correct name is carrier_id. Furthermore, the ON condition is missing the dot (.) operator between the data source name and the field name, which is required to access the fields of the data source1.
* C. ON Sprojection. Carrier Source2.carrier is not valid because Carrier and carrier are not valid fields in the given code. There is no field named Carrier or carrier in any of the data sources. The correct name is carrier_id. Moreover, the ON condition is missing the dot (.) operator between the data source name and the field name, which is required to access the fields of the data source1.
References: 1: ON Condition - ABAP Keyword Documentation

The correct expression to change a given string value 'mr joe doe' into 'JOE' in an ABAP SQL field list is C: SELECT FROM TABLE dbtabl FIELDS Of1, substring(upper('mr joe doe'), 4, 3) AS f2_sub_up, f3,...
This expression uses the following SQL functions for strings12:
* upper: This function converts all lowercase characters in a string to uppercase. For example, upper('mr joe doe') returns 'MR JOE DOE'.
* substring: This function returns a substring of a given string starting from a specified position and with a specified length. For example, substring('MR JOE DOE', 4, 3) returns 'JOE'.
* AS: This keyword assigns an alias or a temporary name to a field or an expression in the field list. For example, AS f2_sub_up assigns the name f2_sub_up to the expression substring(upper('mr joe doe'), 4,
3).
You cannot do any of the following:
* A. SELECT FROM TABLE dbtabl FIELDS Of1, upper(left( 'mr joe doe', 6)) AS f2_up_left, f3,...:
This expression uses the wrong SQL function for strings to get the desired result. The left function
* returns the leftmost characters of a string with a specified length, ignoring the trailing blanks. For example, left( 'mr joe doe', 6) returns 'mr joe'. Applying the upper function to this result returns 'MR JOE', which is not the same as 'JOE'.
* B. SELECT FROM TABLE dbtabl FIELDS Of1, left(lower(substring( 'mr joe doe', 4, 3)), 3) AS f2_left_lo_sub, f3,...: This expression uses unnecessary and incorrect SQL functions for strings to get the desired result. The lower function converts all uppercase characters in a string to lowercase. For example, lower(substring( 'mr joe doe', 4, 3)) returns 'joe'. Applying the left function to this result with the same length returns 'joe' again, which is not the same as 'JOE'.
* D. SELECT FROM TABLE dbtabl FIELDS Of1, substring(lower(upper( 'mr joe doe' ) ), 4, 3) AS f2_sub_lo_up, f3,...: This expression uses unnecessary and incorrect SQL functions for strings to get the desired result. The lower function converts all uppercase characters in a string to lowercase, and the upper function converts all lowercase characters in a string to uppercase. Applying both functions to the same string cancels out the effect of each other and returns the original string. For example, lower(upper( 'mr joe doe' ) ) returns 'mr joe doe'. Applying the substring function to this result returns
'joe', which is not the same as 'JOE'.
References: 1: SQL Functions for Strings - ABAP Keyword Documentation - SAP Online Help 2: sql_func - String Functions - ABAP Keyword Documentation - SAP Online Help

The following are the explanations for each statement:
A: This statement is valid. go_ifl may call method ml with go_ifl->ml(). This is because go_ifl is a data object of type REF TO ifl, which is a reference to the interface ifl. The interface ifl defines a method ml, which can be called using the reference variable go_ifl. The class cll implements the interface ifl, which means that it provides an implementation of the method ml. The data object go_ifl is assigned to a new instance of the class cll using the NEW operator and the inline declaration operator @DATA. Therefore, when go_ifl->ml() is called, the implementation of the method ml in the class cll is executed123 B: This statement is valid. Instead of go_cll = NEW #(...) you could use go_ifl = NEW cll(...). This is because go_ifl is a data object of type REF TO ifl, which is a reference to the interface ifl. The class cll implements the interface ifl, which means that it is compatible with the interface ifl. Therefore, go_ifl can be assigned to a new instance of the class cll using the NEW operator and the class name cll. The inline declaration operator @DATA is optional in this case, as go_ifl is already declared. The parentheses after the class name cll can be used to pass parameters to the constructor of the class cll, if any123 E: This statement is valid. go_ifl may call method m2 with go_ifl->m2(...). This is because go_ifl is a data object of type REF TO ifl, which is a reference to the interface ifl. The class cll implements the interface ifl, which means that it inherits all the components of the interface ifl. The class cll also defines a method m2, which is a public method of the class cll. Therefore, go_ifl can call the method m2 using the reference variable go_ifl. The method m2 is not defined in the interface ifl, but it is accessible through the interface ifl, as the interface ifl is implemented by the class cll. The parentheses after the method name m2 can be used to pass parameters to the method m2, if any123 The other statements are not valid, as they have syntax errors or logical errors. These statements are:
C: This statement is not valid. go_cll may call method ml with go_cll->ifl~ml(). This is because go_cll is a data object of type REF TO cll, which is a reference to the class cll. The class cll implements the interface ifl, which means that it inherits all the components of the interface ifl. The interface ifl defines a method ml, which can be called using the reference variable go_cll. However, the syntax for calling an interface method using a class reference is go_cll->ml(), not go_cll->ifl~ml(). The interface component selector ~ is only used when calling an interface method using an interface reference, such as go_ifl->ifl~ml(). Using the interface component selector ~ with a class reference will cause a syntax error123 D: This statement is not valid. Instead of go_cll = NEW #() you could use go_ifl = NEW #(...). This is because go_ifl is a data object of type REF TO ifl, which is a reference to the interface ifl. The interface ifl cannot be instantiated, as it does not have an implementation. Therefore, go_ifl cannot be assigned to a new instance of the interface ifl using the NEW operator and the inline declaration operator @DATA. This will cause a syntax error or a runtime error. To instantiate an interface, you need to use a class that implements the interface, such as the class cll123

Explanation
Based on the given information, the spfli database table should have the following general settings:
"Storage Type" to "Row Store": This setting determines how the data is stored in the SAP HANA database. Row store is suitable for tables that are accessed by primary key or by a small number of columns. Column store is suitable for tables that are accessed by a large number of columns or by complex analytical queries. Since the spfli table is a large table with over one million rows, and this program is the only one in the system that accesses the table, it is likely that the program will use primary key access or simple queries to access the table. Therefore, row store is a better choice than column store for this table12.
"Load Unit" to "Page Loadable": This setting determines how the data is loaded into the memory when the table is accessed. Page loadable means that the data is loaded in pages of 16 KB each, and only the pages that are needed are loaded. Column loadable means that the data is loaded in columns, and only the columns that are needed are loaded. Since the spfli table is a row store table, and this program will run rarely, it is more efficient to use page loadable than column loadable for this table. Page loadable will reduce the memory consumption and the loading time of the table13.
References: 1: Table Types in SAP HANA | SAP Help Portal 2: [Row Store vs Column Store in SAP HANA | SAP Blogs] 3: [Load Unit | SAP Help Portal]