Three 20- to 30-Minute Cardiorespiratory Training Sessions Per Week, on Nonconsecutive

Three 20- to 30-minute cardiorespiratory training sessions per week, on nonconsecutive days, will maintain cardiorespiratory fitness:

A) as long as the heart rate is in the appropriate target zone.
B) no matter how intensively the individual is exercising.
C) as long as the individual is exercising, regardless of heart rate.
D) as long as the heart rate is above 85 percent of heart rate reserve.