OG5 阅读 Q34

Choice B is the best answer. The previous question asks what the author of the passage suggests about the wisdom of crowds, with the answer being that crowds can be more effective at producing quantitative answers than qualitative results. This is supported in lines 11-14("the...number"): when it comes to guessing a bull's weight or how many gumballs are in a jar, "your guess is probably going to be far from the mark, whereas the average of many people's choices is remarkably close to the true number." 
Choices A, C, and D are incorrect because the lines cited do not support the answer to the previous question about the author's belief about when the wisdom of a crowd is effective. Instead, they simply state that crowds are sometimes wiser than individuals, without explaining when (choice A), put forth a theory held by someone other than the author (choice C), and explain how hypotheses about the wisdom of crowds could be tested (choice D).