OK the the answer you are looking for will be the excretory system because that is the system that releases waste.
Answer:
b. by increasing the heart rate
c. by increasing the respiratory rate
Explanation:
Increased activity of skeletal muscles would require an increased supply of oxygen to these cells to sustain the muscle contraction. Muscle cells perform aerobic cellular respiration in the presence of oxygen and produce ATP molecules to be used during muscle contraction. Therefore, there is an increase in heart rate to pump sufficient blood to the skeletal muscles which in turn ensures enough supply of oxygen. Also, there will be an increase in the respiration rate to inhale the required oxygen.
*Sigh* It's important because conserving energy helps the environment and lets you have a little more pocket money when the bills come around.
