For which of the following tasks can you reuse the implementation from the BOPF public library?

You implement the behavior of a CDS-based BOPF Business Object.

For which of the following tasks can you reuse the implementation from the BOPF public library? Please choose the correct answer.
A . Check for existing foreign keys
B . Auto-fill a Last Changed By field
C . Auto-fill semantic key fields
D . Check for valid dates in input fields

Answer: C