Exam C_ABAPD_2309 Topic 5 Question 72 Discussion

Explanation
The possible replacements for "???" in the CDS view entity definition with an input parameter are A. built-in ABAP type and C. A data element. These are the valid types that can be used to specify the data type of an input parameter in a CDS view entity. A built-in ABAP type is a predefined elementary type in the ABAP language, such as abap.char, abap.numc, abap.dec, etc. A data element is a reusable semantic element in the ABAP Dictionary that defines the technical attributes and the meaning of a field12. For example:
The following code snippet defines a CDS view entity with an input parameter currency of type abap.cuky, which is a built-in ABAP type for currency key:
Define view entity Z_CONVERT With parameters currency : abap.cuky as select from ... { ... } The following code snippet defines a CDS view entity with an input parameter currency of type waers, which is a data element for currency key:
Define view entity Z_CONVERT With parameters currency : waers as select from ... { ... } You cannot do any of the following:
B). A built-in ABAP Dictionary type: This is not a valid type for an input parameter in a CDS view entity. A built-in ABAP Dictionary type is a predefined elementary type in the ABAP Dictionary, such as CHAR, NUMC, DEC, etc. However, these types cannot be used directly in a CDS view entity definition. Instead, they have to be prefixed with abap. to form a built-in ABAP type, as explained above12.
D). A component of an ABAP Dictionary structure: This is not a valid type for an input parameter in a CDS view entity. A component of an ABAP Dictionary structure is a field that belongs to a structure type, which is a complex type that consists of multiple fields. However, an input parameter in a CDS view entity can only be typed with an elementary type, which is a simple type that has no internal structure12.
References: 1: ABAP CDS - SELECT, parameter_list - ABAP Keyword Documentation - SAP Online Help 2:
ABAP Data Types - ABAP Keyword Documentation - SAP Online Help