Answer: watched the nonviolent cartoon
Explanation:
The control group in an experiment is simply the group that is being separated from the rest of the experiment, such that the results can't be influenced by the independent variable that is tested.
In the scenario above, the control group in the experiment is the group that watched the nonviolent cartoon. This is because the experiment was about determining whether watching violent scenes on television increases the frequency of aggressive behavior in children so those that watched the nonviolent cartoon really didn't matter.