A researcher is interested in determining the effectiveness of a new medication that may reduce blood pressure for individuals who have higher than average blood pressure. To determine the effectiveness of the medication, the researcher uses 240 volunteers who have high blood pressure. Volunteers are assigned randomly 50 milligrams of the medicine, 100 milligrams of the medicine, or a placebo. The subjects' blood pressure is measured at the beginning and end of the study. Part A: Identify the subjects, treatments, and response variable.

Part B: What is the advantage of the random assignment of treatment?

Part C: What is an advantage of using a placebo?

Part D: What is a disadvantage of using volunteers?