请教OG逻辑第71题

Maybejessica

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 5percent, with one out of 20workers unemployed. So at any given time if a person knows approximately 50workers, 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. unemplyment 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
正确选项是B，不明白啊~~~

hz032478

我来翻译下
R：百分之90的在这个城市的人说他们认识没有工作的人，这成了我们的当务之急。
S：但是，通常失业率是5%，20个人中间有1个人失业。如果一个人认识50个人，这个人知道的一个或更多的人就是失业的。
B是正确的。B的意思是说失业不是集中在一个区域里的。换句话说就是失业的人是平均分配的。如果没有这个前提，那么失业的人就可以集中在这个城市之中，不论你S说什么，R都是对的。

Maybejessica

谢谢啊~~~