Why do you recommend modeling a data layer in SAP BW/4HANA? Note: There are 2 correct answers to this question.

Why do you recommend modeling a data layer in SAP BW/4HANA? Note: There are 2 correct answers to this question.
A . To pre-define a data layout
B . To fulfill snapshot requirements
C . To immediately display changed entries
D . To homogenize and cleanse data from different sources

Answer: B,D