正解：B,D
In class ZCL_CLASS_A, you use the statement DATA var TYPE *** to declare a data object named var with a data type specified by ***. The data type can be any of the following1:
* A predefined ABAP type, such as i, f, c, string, xstring, and so on.
* A data element from the ABAP Dictionary, such as matnr, carrid, bukrs, and so on. A data element defines the semantic and technical attributes of a data field, such as the domain, the length, the data type, the description, and the value range2.
* A domain from the ABAP Dictionary, such as matnr_d, carrid_d, bukrs_d, and so on. A domain defines the technical attributes of a data field, such as the data type, the length, the output length, the number of decimal places, and the value range3.
* A type defined globally in a class, an interface, or a type pool, such as zcl_class_b=>type_a, zif_interface_c=>type_b, ztype_pool_d=>type_c, and so on. A global type is a type that is defined in a global repository object and can be used in any program or class4.
* A type defined locally in the current class, such as type_a, type_b, type_c, and so on. A local type is a type that is defined in the declaration part of a class and can only be used within the class5.
Therefore, the possible values for *** are B. the name of a data element from the ABAP Dictionary and D. the name of a domain from the ABAP Dictionary. The other options are not valid because:
* A. The name of a type defined privately in class ZCL_CLASS_A is a local type and cannot be used with the DATA statement. A local type can only be used with the TYPES statement5.
* C. The name of a type defined privately in another class is a private type and cannot be accessed from outside the class. A private type can only be used within the class that defines it.
References: 1: DATA - ABAP Keyword Documentation 2: Data Elements - ABAP Dictionary - SAP Online Help 3: Domains - ABAP Dictionary - SAP Online Help 4: Global Types - ABAP Keyword Documentation 5:
Local Types - ABAP Keyword Documentation : Private Types - ABAP Keyword Documentation
