Answer:
B. Is the author an expert in the field on which he/she is reporting?
Explanation:
I think this is the most important question you should ask because it determines if the author is trustworthy or not. By answering it in a possitive way we can be sure he knows what he is talking about and and that he/she has a lot of background to support the ideas presented. As an expert, the author is probably going to use cientific evidence and statistics to prove his/her point.
The other options may tell you somethings about the author's credibility but not in an accurate way. Anectotal evidence is based on the author's experiences that can be analized in a biased or wrong way. The fact that more than one author contributes is not a certainty that their information is correct.
