Answer:
A. glucose and oxygen.
Explanation:
Under normal conditions, muscles derive energy by the process of aerobic cellular respiration. Aerobic cellular respiration is the process of complete oxidation of glucose in the presence of oxygen and occurs in three steps.
1. Glycolysis: Glucose is broken down into two molecules of pyruvate accompanied by the formation of 2 ATPs and 2 NADH.
2. Kreb's cycle: Pyruvate enters the Kreb's cycle in the form of acetyl CoA and is completely broken down into CO2 and H2O. The released energy is stored in form of ATP and reducing powers (NADH and FADH2) are produced.
3. Oxidative phosphorylation: NADH and FADH2 formed during glycolysis and Kreb's cycle are oxidized by giving their electrons to a terminal electron acceptor, the molecular oxygen. The energy of proton motive force is used to form large number of ATPs.
