Dr. Martinez is doing a research study examining the effects of a new headache medication on migraine pain. He decides to divide his participants up into four subject groups,

each one of which will receive a different amount of medication to take when they have a migraine. The participants in group one receive a pill with 10 milligrams of the experimental medication, while the participants in group two receive a pill with 20 milligrams. Those assigned to group three receive a pill with 30 milligrams, while those in group four receive a placebo pill that has zero milligrams of the medication. Which of the subject groups is the control group in this study?
a. Group one
b. Group two
c. Group three
d. Group four

Answer: D