Answer:
The correct option is C.
repaying an oxygen debt.
Explanation:
This is because while running, humans breath shallowly which could not provide the oxygen requirement for the respiratory system and fit in for blood need.
After running, you tend to breathe heavily because your muscle work very hard , the body use more oxygen and produced more carbondioxide, therefore the lungs and respiratory system must try to provide more oxygen to the blood. sympathetic nerves stimulate respiratory muscles
so as to increase the rate at which we breathe.
