When obtaining assessment data from collateral sources, social workers should:

A) ​exercise discretion.
B) ​avoid consulting collateral contacts suggested by clients.
C) ​avoid consulting family members of clients.
D) ​operate anonymously.

Social workers should exercise discretion when obtaining assessment data from collateral sources to ensure that confidential information is kept private and only shared on a need-to-know basis. This can help maintain the trust of clients and their collateral contacts. Avoiding collateral contacts suggested by clients or consulting family members of clients may not be necessary or appropriate in all cases, so it is important to make a judgement based on each individual situation. Operating anonymously may also not be necessary or appropriate, and could potentially hinder effective communication and collaboration with collateral contacts. Therefore, the best choice is to exercise discretion.