I was stuck between A and D but I chose A because D was attempting to give an explanation rather than expanding/strengthening the stimulus hypothesis(genetics).

I'm finally starting to predict the answers before reading the answer choices. I didn't even think it was possible.

I chose B, but I knew that because the answer stated "all" skeptics, it could be wrong. I would've never guessed D, and it still doesn't make sense for the answer to be D. Help!