The correct option is C: Take your heart or pulse rate. Heart or pulse rate helps one to determine the intensity of exercise.
<u>EXPLANATION:</u>
Exercises can be low intensity, moderate intensity or high intensity. The intensity measures how hard a person works when exercising.
For moderate intensity exercise, the heart rate must be "50-70% "of the target heart rate.
For high intensity exercises, the heart rate must be "70-85%" of the target heart rate. For high intensity exercises, the heart rate will come higher than usual.