Explanation
The sequence in which the constructors will be executed is as follows:
Class constructor of superl. This is because the class constructor is a static method that is executed automatically before the class is accessed for the first time. The class constructor is used to initialize the static attributes and components of the class. The class constructor of the superclass is executed before the class constructor of the subclass, as the subclass inherits the static components of the superclass12 Class constructor of subl. This is because the class constructor is a static method that is executed automatically before the class is accessed for the first time. The class constructor is used to initialize the static attributes and components of the class. The class constructor of the subclass is executed after the class constructor of the superclass, as the subclass inherits the static components of the superclass12 Instance constructor of superl. This is because the instance constructor is an instance method that is executed automatically when an instance of the class is created using the statement CREATE OBJECT.
The instance constructor is used to initialize the instance attributes and components of the class. The instance constructor of the superclass is executed before the instance constructor of the subclass, as the subclass inherits the instance components of the superclass. The instance constructor of the subclass must call the instance constructor of the superclass explicitly using super->constructor, unless the superclass is the root node object12 Instance constructor of subl. This is because the instance constructor is an instance method that is executed automatically when an instance of the class is created using the statement CREATE OBJECT.
The instance constructor is used to initialize the instance attributes and components of the class. The instance constructor of the subclass is executed after the instance constructor of the superclass, as the subclass inherits the instance components of the superclass. The instance constructor of the subclass must call the instance constructor of the superclass explicitly using super->constructor, unless the superclass is the root node object12 References: Constructors of Classes - ABAP Keyword Documentation, METHODS - constructor - ABAP Keyword Documentation

Explanation
Incomplete ABAP types are types that do not specify all the attributes of a data type, such as the length, the number of decimal places, or the value range. Incomplete types can only be used for the typing of field symbols and formal parameters, not for the definition of data objects or constants. Incomplete types can be either predefined or user-defined1.
The following are incomplete ABAP types:
C). C is a type for character strings with a generic length. The length of the character string has to be specified when a data object or a constant is defined with this type. For example, DATA text TYPE c LENGTH 10 defines a data object named text with a type c and a length of 10 characters2.
D). P is a type for packed numbers with a generic length and a generic number of decimal places. The length and the number of decimal places of the packed number have to be specified when a data object or a constant is defined with this type. For example, DATA amount TYPE p LENGTH 8 DECIMALS 2 defines a data object named amount with a type p, a length of 8 bytes, and 2 decimal places3.
The following are not incomplete ABAP types, because they specify all the attributes of a data type:
A). String is a type for variable-length character strings. The length of the character string is determined at runtime and can vary from 0 to 2,147,483,647 characters. The length does not have to be specified when a data object or a constant is defined with this type. For example, DATA text TYPE string defines a data object named text with a type string and a variable length4.
B). T is a type for time values in the format HHMMSS. The length of the time value is fixed at 6 characters and does not have to be specified when a data object or a constant is defined with this type.
For example, DATA time TYPE t defines a data object named time with a type t and a length of 6 characters.
References: 1: Generic ABAP Types - ABAP Keyword Documentation 2: C - ABAP Keyword Documentation 3: P - ABAP Keyword Documentation 4: String - ABAP Keyword Documentation : T - ABAP Keyword Documentation

Explanation
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.
References: CDS Data Model Views - ABAP Keyword Documentation, CDS Service Definitions - ABAP Keyword Documentation, CDS Service Bindings - ABAP Keyword Documentation, CDS Projection Views - ABAP Keyword Documentation