Final answer:
Glycolysis is used in anaerobic exercises to break down glucose into ATP and lactic acid when oxygen supply is low. The phosphagen system provides a quick supply of ATP at the start of high-intensity exercises. The correct answer is C, as both systems are employed during anaerobic activities.
Step-by-step explanation:
The glycolysis and phosphagen systems are primarily used in different types of exercise based on the presence or absence of oxygen. Glycolysis can occur either aerobically or anaerobically, but in the context of exercise, it is used in anaerobic exercise, such as weight lifting or sprinting, where there is a faster demand for ATP than oxygen supply can maintain. During anaerobic glycolysis, glucose is broken down to produce ATP and lactic acid when oxygen levels are low. On the other hand, the phosphagen system (also known as the creatine phosphate system) is primarily activated at the beginning of high-intensity exercise and provides ATP very quickly, but only for a short duration.
Therefore, the correct answer to the question is: C. Both glycolysis and the phosphagen system are used in anaerobic exercise.