Question:
This question asks what type of variable exercise is in the study described. All study participants were instructed to eat and exercise as normal. Any variable held constant between the experimental and control group is a controlled variable. Since exercise is the same in both groups, it is a controlled variable. The independent variable is the factor that is changed between the two groups; in this experiment, this is folic acid supplementation. The dependent variable is the quantity that is measured—blood pressure in this experiment. The control group is not a variable but is a group of subjects that is identical to the experimental group except for the one dependent variable that is being studied. In this study, the people receiving the placebo are the control group.