OFFICIAL EXPLANATION


The correct answers are D and E.

Choice D, "challenge," means "a demanding or stimulating situation or question" and "conundrum," choice E, is a "puzzling question or problem" and are the better pair of synonyms for the context. Choices A and C, "paradox" and "enigma," are close synonyms, meaning "a seemingly contradictory statement that may be true" and "something seemingly inexplicable, baffling," respectively. Choice B, "provocation," means "something that provokes or incites, stirring to action" and doesn't fit the context. Choice F, "paradigm," means "typical example or a relationship of ideas to one another" and doesn't fit, nor does it or choice B have synonyms on the list.