Problem behavior in children can usually be dealt with effectively through reinforcement.

Problem behavior in children can usually be dealt with effectively through differential reinforcement.
Differential reinforcement refers to the implementation on reinforcing only in the right reaction or behavior you want to increase and implementing extinction to all other responses. It consists of two parts, the withholding reinforcement for the challenging behavior and second the providing reinforcement for an appropriate replacement behavior.

Idont know which one is right   but i know that c is wrong and a might be wrong