GMAT逻辑OG12-71问题!

题目

GMAT逻辑OG12-71问题!
71.Roland:The alarming fact is that 90 percent of the people in this country now report that they know someone who is unemployed.
Sharon:But a normal,moderate level of unemployment is 5 percent,with one out of 20 workers unemployed.So at any given time if a person knows approximately 50 workers,one or more will very likely be unemployed.
Sharon’s argument relies on the assumption that
(A) normal levels of unemployment are rarely exceeded
(B) unemployment is not normally concentrated in geographically isolated segments of the population
(C) the number of people who each know someone who is unemployed is always higher than 90 percent of the population
(D) Roland is not consciously distorting the statistics he presents
(E) knowledge that a personal acquaintance is unemployed generates more fear of losing one’s job than does knowledge of unemployment statistics.
为什么选B?C哪里不对?

答案

R说国家里90%的人声称自己知道有人失业.S说 正常的失业率是5% 也就是每20个工作的人中一人失业.所以任何时候如果某人认识50个workers,其中至少有一人很可能失业.题目只要分析S的结论依据B前提是 失业人口并不集中于...