In ABAP SQL, the syntax to retrieve the association field of a CDS view is to use the @ sign followed by the association name and the field name, separated by a period sign (.). For example, to retrieve the association field _Airline-Name of a CDS view, the syntax is @_Airline.Name. This syntax allows the access to the fields of the target data source of the association without explicitly joining the data sources1. The other options are incorrect because they use the wrong symbols or formats to access the association field.

The order in which objects are created to generate a RESTful Application Programming application is A, D, C, B. This means that the following steps are followed:
First, a database table is created to store the data for the application. A database table is a CDS DDIC-based view that defines a join or union of database tables. A database table has an SQL view attached and can be accessed by Open SQL or native SQL.
Second, a data model view is created to define a data model based on the database table or other CDS view entities. A data model view is a CDS view entity that can have associations, aggregations, filters, parameters, and annotations. A data model view can also define the behavior definition and implementation for the business object.
Third, a service definition is created to define the service interface for the application. A service definition is a CDS view entity that defines a projection on a data model view or another service definition. A service definition can also define service metadata, such as service name, version, description, and annotations.
Fourth, a service binding is created to define the service binding for the application. A service binding is a CDS view entity that defines a projection on a service definition. A service binding can also define the service protocol, such as OData V2, OData V4, or REST, and the service URL.

The ABAP SQL clause that allows the use of inline declarations is the INTO clause. The INTO clause is used to specify the target variable or field symbol where the result of the SQL query is stored. The INTO clause can use inline declarations to declare the target variable or field symbol at the same position where it is used, without using a separate DATA or FIELD-SYMBOLS statement. The inline declaration is performed using the DATA or @DATA operators in the declaration expression12. For example:
The following code snippet uses the INTO clause with an inline declaration to declare a local variable itab and store the result of the SELECT query into it:
SELECT * FROM scarr INTO TABLE @DATA (itab).
The following code snippet uses the INTO clause with an inline declaration to declare a field symbol <fs> and store the result of the SELECT query into it:
SELECT SINGLE * FROM scarr INTO @<fs>.
You cannot do any of the following:
FROM: The FROM clause is used to specify the data source of the SQL query, such as a table, a view, or a join expression. The FROM clause does not allow the use of inline declarations12.
INTO CORRESPONDING FIELDS OF: The INTO CORRESPONDING FIELDS OF clause is used to specify the target structure or table where the result of the SQL query is stored. The INTO CORRESPONDING FIELDS OF clause does not allow the use of inline declarations. The target structure or table must be declared beforehand using a DATA or FIELD-SYMBOLS statement12.
FIELDS: The FIELDS clause is used to specify the columns or expressions that are selected from the data source of the SQL query. The FIELDS clause does not allow the use of inline declarations. The FIELDS clause must be followed by an INTO clause that specifies the target variable or field symbol where the result is stored12.