Mismatched conclusion and premises. (A) concludes that an expert is correct, whereas the stimulus concludes that a non-expert is incorrect. (Because an unbiased expert disagrees.) There’s no less credible source to doubt in (A), unlike the stimulus.

(B) concludes that we should doubt a claim that is contradicted by an unbiased source with direct knowledge. Penwick found bones that he claims are dinosaur bones. But paleontologist Gardner says, after examination, that they can’t be dinosaur bones. Since Gardner is unbiased, we should doubt Penwick. This parallels the stimulus.

Mismatched premises and conclusion. (C) concludes that an expert is correct, because he’s the only one who’s examined something. The stimulus concludes that a non-expert is likely incorrect, because an unbiased expert made an examination and disagrees. So neither the conclusion nor the premises are parallel.

Mismatched premises and conclusion. (D) concludes that we should accept a reporter’s conclusion, even though he has reason to be biased. The stimulus concludes that we should doubt a reporter’s conclusion, because an unbiased expert disagrees. Neither the conclusion nor the premises are parallel here.

Mismatched premises. (E) concludes that, because the source is biased, we should doubt a claim. The stimulus concludes that, because an unbiased expert disagrees, we should doubt a claim.