Professor Rahn Is Conducting a Study on the Effects of Caffeine

Professor Rahn is conducting a study on the effects of caffeine on college students' study habits. His research question is: Will students who consume moderate doses of caffeine prior to studying perform better on an exam than students who do not consume any caffeine prior to studying? Professor Rahn randomly assigns students to one of two groups: One group is given two caffeinated beverages prior to studying, and the second group is given beverages without caffeine. Both groups of students believe they are consuming caffeinated beverages. According to research on experimental controls, what is the second group of participants receiving?