Answer:
(D) Strenuous exercise has caused her body to be in oxygen debt, and she is breathing hard while lactate is transported to the liver. This is a result of anaerobic respiration.
Explanation:
As Frida was exercising, her muscle cells were undergoing a frantic pace of metabolism (contraction and relaxation), where oxygen supply did not supply the required effort, thus causing muscle fatigue and heavy breathing.
Physical activity is synonymous with moving muscles. The more muscle fibers strive to accomplish a task, the more they consume the oxygen brought into the bloodstream. When this occurs, the body begins to breathe hard as lactate is transported to the liver.
This forces the lungs to work at a fast pace, as they are responsible for oxygenation. The heart also speeds up because it needs to pump blood more vigorously. This is why during exercise the heart rate and breathing rate increase and we breathe heavily.
