Explanation
Correct answer: D.
Choice D is the best answer. This sentence is arguing that new evidence contradicting popular beliefs about “tulip mania” should cast doubt on those beliefs. “Therefore” is a cause-and-effect transition, which fits perfectly in this context.
Why the other choices are wrong
Choice A
Choice A is incorrect. This choice uses an exemplification transition, which doesn’t make sense here. Skepticism about the popular beliefs is not an example of recent evidence contradicting those beliefs—rather, skepticism is an effect of that recent evidence.
Choice B
Choice B is incorrect. This choice uses a disagreement transition. But this sentence doesn’t disagree with the previous sentence. Instead, it connects a cause from the previous sentence (new evidence that tulip mania was not as disastrous as thought) to an effect (that we should look with skepticism upon the myth about its disastrousness).
Choice C
Choice C is incorrect. This choice uses a disagreement transition. But this sentence doesn’t disagree with the previous sentence. Instead, it connects a cause from the previous sentence (new evidence that tulip mania was not as disastrous as thought) to an effect (that we should look with skepticism upon the myth about its disastrousness).