Critical Reasoning

Hi,

The correct answer is B but I thought A is better answer because A weakens the statement more...
Can anyone explain why B is better answer??

Thanks@

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?

(A) Since 1960 the teenage unemployment rate has risen when the minimum wage has risen.
(B) Since 1960 the teenage unemployment rate has risen even when the minimum wage remained constant.
(C) Employers often hire extra help during holiday and warm weather seasons.
(D) The teenage unemployment rate rose more quickly in the 1970’s than it did in the 1960’s.
(E) The teenage unemployment rate has occasionally declined in the years since 1960.

The argument can be weakened if we can show that the teenage unemployment rate has risen even when the minimum wage was lowered or that the teenage unemployment rate has risen even when the min wage remained constant.
B address one of the above factors and is therefore correct.

Regarding A:The rise of minimum wage is beyond the scope of the argument since the argument is limited to subminimum wages.

A is incorrect, because it can strengthen rather than weaken the argument. If the unemployment rises whenever minimum wage rises, there is a possibility that it could stop rising if the minimum wage did not increase.
B suggests that unemployment rate doesn't necessarily change with minimum wage change.

Well i also thin that B is the answer