Answer:
Control group
Explanation:
A control group is necessary in all experiments that require a comparison. A control group and an experimental group are both included in an experiment. These two need to be identical in every way with the exception of the fact that the experimental group will be subjected to a treatment that is believed to have a particular outcome. In this case, it is difficult to know whether the drink really has the desired effects or not, as we are not aware of the results of a control group.