Answer:
C.
70%-85%
Step-by-step explanation:
In sports, heart rate (HR) is used to evaluate the intensity of exercise. There is a linear relationship between heart rate and load intensity. Maximum heart rate (HRmax) is the maximum number of contractions a heart can perform in 1 minute. Maximum heart rate can vary significantly in different people. The American Heart Association recommends a target heart rate of hight intensity exercise: 70% to about 85% of your maximum heart rate