Which of the following advertisements effectively appeals to logic?
A. "Lose weight, feel great! Sign up now for a free one-month trial of our new exercise program."
B. "Feeling down? Lacking energy? Our new exercise program will help you kick-start your life. Sign up now!"
C. "Recent studies have shown that people who exercise live longer than people who do not. Come try our new exercise program. Free one-month trial."
D. "Exercise is good for you! Sign up now for a free month of our new exercise program."