Please provide a detailed explanation to the following question and explain why the other answer choices are wrong.

[13] The refusal of a client's legal counsel to provide a representation on the legality of a particular act committed by the client is ordinarily A. Sufficient reason to express a subject to opinion. B. Considered to be a scope limitation. C. Insufficient reason to modify the auditor's report because of the legal counsel's obligation of confidentiality. D. Proper grounds to withdraw from the engagement