A medical researcher conducted a study to investigate whether exercising can lower cholesterol. From a sample of 150 adult volunteers with high cholesterol, 75 were randomly assigned to pursue an exercise program that includes daily jogging and strength training. The remaining 75 were asked to refrain from vigorous activity. At the end of six months, the people in the exercise group substantially reduced their cholesterol, while the people in the no-exercise group did not experience a reduction. Which of the following is the most appropriate conclusion? (A) There is evidence that exercise causes a reduction in cholesterol, and the conclusion can be generalized to all adults. (B) There is evidence that exercise causes a reduction in cholesterol, and the conclusion can be generalized to all adults who exercise. (C) There is evidence that exercise causes a reduction in cholesterol, and the conclusion can be generalized to adults similar to these study volunteers with high cholesterol. (D) Although cause-and-effect cannot be established, there is an association between exercising and a reduction in cholesterol for the population of all adults. (E) Although cause-and-effect cannot be established, there is an association between exercising and a reduction in cholesterol for the population of all adults who exercise.