The correct answer is option B, that is, increased muscle mass - increased mitochondria - increased cellular respiration - increased ATP.
The generation of ATP takes place inside mitochondria using energy stored in the food. Some cells exhibit more mitochondria than others. For example, the muscle cells have an ample amount of mitochondria that permits them to react promptly to the need for performing a function.
Mitochondria are considered as the powerhouse of the cell, as they turn oxygen and nutrients into fuel for the body. The muscles need more mitochondria as they are functioning much harder in comparison to other cells like fat cells that make the fat cells to discharge energy gradually, on the other hand, the muscle cells do that much quicker.