请教一道cr（新东方题）

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,q new lower legalwage for teenagers,the teenager unemployment reat,which has been rising since 1960,will no longer increase.

which one weaken the argue above?

since 1960 the teenager unemployment reat has risen even when the minimum wage remained constant.

我想不明白为什么是这个呢？

最小工资不变，失业率照样升高。怎么会消弱结论呢？