Within the last year，scientists have come closer than ever _______ ．A）to deciding which of the questions is rightB）to decide which of the questions is rightC）deciding whether the question is right or notD）and decided which of the questions is right

choose C  !

Within the last year，scientists have come closer than ever _______ ．A）to deciding which of the questions is rightB）to decide which of the questions is rightC）deciding whether the question is right or notD）and decided which of the questions is right
A.
come closer to 是一个动词词组，意思是”接近“，后面加名词
than ever 是 "比前都“

选择A是错的，因为to后面要跟原形动词。也就是说come closer than ever to  decide.........才是对的。to decide......是结果状语。than ever是时间频度状语。
故此我选择B.

A) to deciding which of the questions is right.
The phrase "come closer than ever" implies that the decision has not yet been made, and that progress has been made towards making the decision. Choice A, "to deciding which of the questions is right," best reflects this idea. Choice B, "to decide which of the questions is right," suggests that the decision has not yet been made, but does not reflect the idea that progress has been made. Choice C, "deciding whether the question is right or not," suggests that the decision is still in progress but it's not specific about what decision is being made. Choice D, "and decided which of the questions is right," implies that the decision has already been made, which contradicts the idea that progress has been made.