Answer:
A. Group A only
Explanation:
The experimental group was group A, on the other hand, the control group was group B.
An experimental group is a set of people that receives treatment in an experiment, supplement daily in this case.
In every experiment, there is a test of subjects that are exposed to the treatment that is being studied called experimental group. But also, they must perform the same experiment with another test of subjects not exposed to the new treatment called control. In other to see if they are any differences between the two of them.
In this case, the treatment supplement daily was given to the group A. And the placebo or sugar pill with nothing in it was given to the group B to compare and confirm if the treatment actually works.