Why not A?

The question asks us about the author's OBJECTION. I thought their objection was that it's probably not an asteroid; it's probably a terrestrial cause. Of these answers, only A is suitable, as terrestrial causes. But this says E is correct, pertaining to a comet, which the author objects to. It's not clear to me why a question asking about the objection would be answerable by a parallel to the objectionable thing