We May Have Good Reason to Doubt the Credibility of a Source

We may have good reason to doubt the credibility of a source if _____.

A) the issue is not one that can be settled by expert opinion
B) None of the answers are correct
C) the source is not a genuine expert or authority on the topic he or she is discussing and the issue is not one that can be settled by expert opinion
D) the source is not a genuine expert or authority on the topic he or she is discussing