C. rhetorical
Explanation:
A rhetorical question is a question (such as "How could I be so stupid?") that's asked merely for effect with no answer expected. The answer may be obvious or immediately provided by the questioner.
B is certainly the moral answer. When a source is shown to be untrustworthy, citing it only amplifies the problem. It is similar to how fake news stories have become a problem on social media. Often people share them without taking time to confirm they are true.
