During the 19805 22,000 physicians over the age of 40 agreed to participate in a long-term study called the Physicians Health Study. The question investigated was whether aspirin helps lower the rate of heart attacks for adults over the age of 40. The physicians were randomly assigned to take aspirin or take a placebo. There are other explanatory variables such as the amount of exercise a physician got, that we would expect to be associated with the response variable. We should 0 block physicians according to level of exercise in their weekly routine (none, low, moderate, high). 0 none of the above. O randomly assign physicians to groups with low or high exercise levels. O ignore the amount of exercise a physician got because heart attack is a genetic condition