Why is B correct? Why is D wrong?

Hi Manvir, thanks for the question. In this question, we are looking to identify the answer choice which contains an idea from passage A that author B would disagree/be most sceptical about. Answer choice B states that positive evidence plays no role in supporting a theory. Author B would disagree with this because the positive evidence regarding correctly predicting Mercury's orbit solidified Einstein's theory. Answer choice D should, for future reference, be a simple answer choice to dismiss. Author B never discussed logical asymmetry. When one speaker does not have an opinion on an answer choice, then it cannot be the point of disagreement. I hope this helps. Please let me know if you have any other question!