大全section2-8（找不到这题的讨论啊）

8．Teenagers are often priced out of the labor market by the government-mandated minimum-wage level because employers cannot afford to pay that much for extra help. Therefore, if Congress institutes a subminimum wage, a new lower legal wage for teenagers, the teenage unemployment rate, which has been rising since 1960, will no longer increase.

Which of the following, if true, would most weaken the argument above?

(B) Since 1960 the teenage unemployment rate has risen even when the minimum wage remained constant.

(E) The teenage unemployment rate has occasionally declined in the years since 1960. （B）

结论是IF Congress institutes a subminimum wage, a new lower legal wage for teenagers, the teenage unemployment rate, which has been rising since 1960，will no longer increase.

而E否定has been rising since 1960，不能削弱结论。这是条件结论的一般解题原则。

比如如果结论是：如果我是你，我GMAT就能考800分，而我反驳结论用，我不是你，是削弱不了结论，我GMAT就能考800分的。

B 对原文的weaken 是不是建立在这样的assumption:1960年的minimum wage(成人)一直没有变化,在现在看来已经是很低了.所以没有必要建立 Teenage的minimum wage.

求教

我也不明白B的逻辑是什么，请nn指教