D. All of the above
Step-by-step explanation:
A. You need to drink fluid during exercise to replace the fluids you lose when you sweat. That way, you'll reduce the risk of heat stress, maintain normal body function, and maintain performance levels
B. If you don't take care and prepare when exercising in the heat, you risk serious illness. The exercise, as well as the air temperature and humidity, can increase your core body temperature. Regardless of the activity, if you exercise outdoors in hot weather you will want to take precautions to prevent heat-related illnesses.
C. Choosing when where and how to exercise helps people achieve their fitness goals and is safe, sustainable, and enjoyable (or at least tolerable). Exercise should also offer some degree of challenge in at least some workouts so that the exercise increases or sustains fitness levels.