Question

system of reinforcement in which only a portion of responses is reinforced
schedule of partial reinforcement
schedule of partial offensive
schedule of partial detachment
schedule of partial entrenchment
schedule of partial counterattack

Explanation:

In psychology, a schedule of partial reinforcement is a system where only some of the responses are reinforced. This is in contrast to continuous reinforcement where every response is reinforced. The other options are not relevant terms in the context of reinforcement.

Answer:

A. schedule of partial reinforcement