Dr. Grey discovers a new drug that she hypothesizes will increase fat storage in rabbits. She designs an experiment to test her hypothesis. Dr. Grey separates twelve rabbits into two equal groups and measures their body fat individually. She gives one group of rabbits the drug but does not give the drug to the other group. She keeps everything else about the rabbits' living environment the same, including the amount of water and food provided. After a month, she measures the body fat of the rabbits in both groups. What is the control in Dr. Grey's experiment? A. the quantity of exp