A) Says that it guarantees the falsity. That's not the case—a lack of evidence is not evidence itself that it doesn't exist.
B) Saying there's a lack of evidence for it doesn't support that he was a member of a church—the latter assertion is presented as a fact, and the former is presented as supporting the overall argument.
C) It doesn't question his credibility. The speaker could still hold Fraenger in high regard, but just disagree with him on this one issue.
D) This is correct. The assertion that there's no evidence for Fraenger's assertion casts doubt on its reliability as a hypothesis. It's saying that there is insufficient proof for such a large hypothesis.
E) This doesn't touch on whether the subject matter is important. They both seem to be addressing the same subject, so E is irrelevant.
