When exercising in the heat, you should a. wear tight-fitting clothes to absorb your sweat b. dress in layers c. choose dark colored clothing d. vary the intensity and duration of the exercise

The correct answer is D. When exercising in the heat, you should vary the intensity and duration of the exercise. Wearing tight-fitting clothing will not cause your sweat to be absorbed, wearing layers will cause your body temperature to rise even further, and wearing black clothing will cause more heat to be absorbed. Therefore, all of the alternative answers will not help contribute to a healthy exercise routine.