Some credit card companies are making credit scores available to all of their customers on their monthly statements. What impact would you expect to see as a result of this change?

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?