user1937
GMATNinja can you please share your thoughts here.
Why is (A) incorrect?
There are two wages to be considered here - minimum wage (which does not apply to teenagers), and sub-minimum wage (which applied to teenagers).
If minimum wage increases, companies would hire teenagers (as minimum wages don't apply to them) at a wage lower than that of non-teenagers. So there wouldn't be a need to introduce a new sub-minimum wage.
Why does this not weaken the argument more than that of (B)?
The "subminimum" wage is only hypothetical and does not yet exist ("
if Congress institutes a subminimum wage, a new lower legal wage for teenagers...").
The author argues that IF a subminimum wage for teens was created, THEN the teenage unemployment rate would no longer increase. But for now, there's only one
single minimum wage that applies to everyone.
An increase in that single (or universal) minimum wage would, according to the author, only further price teens out of the labor market, so (A) is actually consistent with the author's argument.
I hope that helps!