Which aerobic exercise plan is the most well-balanced?
A) 15 minutes to warm up, 15 minutes of aerobic activity, 15 minutes to cool down
B) 5 minutes to warm up, 25 minutes of aerobic activity, 0 minutes to cool down
C) 0 minutes to warm up, 15 minutes of aerobic activity, and 15 minutes to cool down
D) 5 minutes to warm up, 20 minutes of aerobic activity, 5 minutes to cool down