An Experimenter Studies the Relationship Between Caffeine and Reaction Time

Multiple Choice

An experimenter studies the relationship between caffeine and reaction time.She designs her experiment with four groups.Group 1 receives 100 mg of caffeine each in their cups of coffee,group 2 receives 200 mg of caffeine each in their cups of coffee,group 3 receives 300 mg of caffeine each in their cups of coffee,and group 4 receives no coffee.Twenty minutes later,participants from all the groups are given a reaction-time test. In this experiment,which group is the control group?

A) group 4
B) group 3
C) group 2
D) group 1