请教各位大侠，对OG 139的疑问

Questions 138-139 are based on the following.

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 1 out of 20 workers unemployed. So at any given time if a person knows approximately 50 workers, 1 or more will very likely be unemployed.

138. Sharon's argument is structured to lead to which of the following as a conclusion?

(A) The fact that 90% of the people know someone who is unemployed is not an indication that unemployment is abnormally high.

(B) The current level of unemployment is not moderate.

(C) If at least 5% of workers are unemployed, the result of questioning a representative group of people cannot be the percentage Roland cites.

(D) It is unlikely that the people whose statements Roland cites are giving accurate reports.

(E) If an unemployment figure is given as a certain percent, the actual percentage of those without jobs is even higher.

139. 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% 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

138没有问题，问题出在139。

首先，我们肯定138的结论，二者的论点没有任何联系。答案选B，似乎看上去也只有这个稍微顺眼一点了，但是，答案解释的很奇怪。Sharon’s argument assumes that people are generally similar in how likely they are to have among their acquaintances people who are unemployed. Since heavy concentrations of unemployment in geographically isolated segments of the population would produce great differences in this respect, Sharon’s argument assumes few, if any, such concentrations. Choice B is the best.

这题问假设，那么取非B，if concentrated → not similar

但是，它是如何得出“SIMILAR”这个假设的呢？在题干里根本没有啊，是不是ETS为了自圆其说，乱盖的呢？