I believe it is B. Because during vigorous exercise, the heart rate and depth of breathing increases to supply muscles with more oxygen.
The answer is true...hope that helped
To increase their muscle mass and strength. The main anabolic steroid hormone produced by your body is testosterone. Testosterone has two main effects on your body: Anabolic effects promote muscle building.
your heart speeds up so more blood can reach your muscles. Muscles use oxygen to create the stuff needed for the work in exercise.your heart rate returns to its normal or resting rate fairly quickly
