Question

17. A psychologist is studying the effects of orange juice on the prevention of colds. She has one group drink a glass of orange juice every day for the month of December. A second group drinks a glass of orange juice once a week during December, while a third group is not given any orange juice at all during this time period. Previous medical histories were obtained for all the participants. In January, she records how many colds each participant gets over the entire month. In this study, the independent variable is A) the severity of the colds in January B) the number of colds each participant got in January C) the prior medical histories D) drinking orange juice every day E) the amount of orange juice consumed