Glucose can be:

Glucose serves multiple important functions in the body, primarily as a key energy source. It can be used for ATP production, which is the energy currency of the cell. During cellular respiration, glucose is broken down through glycolysis and the citric acid cycle, leading to the production of ATP. This process helps supply the energy required for various bodily functions and physical activity.

In addition to immediate energy production, glucose can also be stored as muscle glycogen. Glycogen acts as a readily accessible energy reserve during physical activity, particularly in high-intensity exercise, and is crucial for maintaining workout performance and endurance. When the body needs energy and glucose is not available in the bloodstream, it can break down glycogen back into glucose.

While the option that includes excretion of glucose to lower pH balance suggests a role that is not typical for glucose, the primary functional roles of glucose as both an energy source and a stored form of energy (as glycogen) sufficiently underscore why the correct answer encompasses both of those functions. Thus, the choice affirming that glucose can be used for ATP production and stored as muscle glycogen captures the essence of glucose's dual role in energy metabolism.