Astudent is conducting their science experiment on the effect of caffeine on dogs. he has 3 groups of test subjects. the 1st group of dogs receives plain water. the 2nd group of dogs receives 10 mg of caffeine each, and the 3rd group receives 50 mg of caffeine each. he will measure their activity levels by recording how long each dog runs without stopping, after giving them the pills. what is the control group in this experiment?

The control group are the dogs that receive plain water

Explanation:

In every research experiment we need a standard or control group in which we can compare the effects of the treatments. The control group is tested in normal conditions (we always know what’s is going to happen), in this case, the normal condition is that the dog dirk plain water. The tested group is in which we want to know the effect of the treatment, we do not know what is going to happen ( we want to know what happen if the dog consumes caffeine before runs).

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: