Determine whether the study depicts an observational study or an experiment. Professional weightlifters are randomly divided into two groups. One group is given a diet of mostly protein; the other is given a diet of mostly carbohydrates. After 1 week, each group is given a lifting test to compare strength. Choose the correct description of the study. O A. The study is an observational study because the researchers control one variable to determine the effect on the response variable. O B. The study is an observational study because the study examines individuals in a sample, but does not try to influence the variable of interest. O C. The study is an experiment because the researchers control one variable to determine the effect on the response variable. O D. The study is an experiment because the study examines individuals in a sample, but does not try to influence the variable of interest