Answer:
The control group are the dogs that receive plain water
Step-by-step 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).