The purpose of a control group in an experiment is to prove the prediction. for comparison to the other test groups. to control the dependent variable. for comparison to the results of other experiments. to prove the hypothesis.

That's right.

Explanation:

The design described refers to a quasi-experimental research. In this design you need to set two groups at least, a control group and an experimental group.

So, to prove the hypothesis we need to apply the stimulus to the experimental group, and control group doesn't receive it. In this way, we'll be able to comparison the two groups and see the differences between.

Therefore, by comparison we demonstrate our hypothesis, that's why is right your proposition.

answer; overt behavior;