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 one receives 100 mg of caffeine each in their cups of coffee;group two receives 200 mg of caffeine each in their cups of coffee;group three receives 300 mg of caffeine each in their cups of coffee;and group four 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 four
B) Group three
C) Group two
D) Group one