Answer:
B. While it's true that students with after-school jobs would be affected, more time spent learning would only benefit their future job prospects.
Step-by-step explanation:
First of all, let's define "counter claim", it refers to a claim that is made to oppose a previous claim. In this case, we want to answer in a polite way the counterclaim that opposes to the extention of the school day. Therefore we want to defend the idea of an extra hour in school. Their argument is that the students with jobs are going to be affected. A direct allusion to that argument is then needed. The chosen answer (B) not only adresses the argument presented in the counterclaim, it does it in a civil way as it is presented as a logic argument that seeks benefit for everyone. It accepts the idea stablished in the counterclaim as an importan factor but it points out the fact that in a long term it's benefits will be more important than it's cons.
The other options state in a rude way that the counterclaim is wrong, they don't make the effort on trying to undestand their point of view. They use preconceptions of the people against the extra hour.