5. At a local health club, a researcher samples 75 people whose primary exercise is cardiovascular and 75 people whose primary exercise is strength training. The researcher's objective is to assess the affect of type of exercise on cholesterol. Each subject reported to a clinic to have his or her cholesterol measured. The subjects were unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of the subject's type of exercise. This approach is: Oa. an observational study. 0 b. an experiment, but not a doubleblind experiment. 8c fundamentally awed because only a welldesigned experiment with randomized assignment to ' treatments can be used to determine a cause-andeffect relationship. 0d. a double-blind exneriment