Answer:
Control group
Explanation:
In an experiment, the group which receives the treatment (in this case injection of actual drug) is known as experimental group because the experiment is being conducted on it. While on the other hand the group which do not receive the treatment is known as control group. The results obtained from the experimental group are compared with the control group to determine the effectiveness of the treatment.
Well, the food is in the environment. I would like to compare it with how bacteriae feed (however my biology is quite rusty), that is, they engulf their food and they "digest" -- not the proper term, since there are no organs to do real digestion -- it.