Answer:
C. ATP.
Step-by-step explanation:
During the process of aerobic cellular respiration, energy is said to be released in three main stages: glycolysis, Krebs cycle and oxidative phosphorylation (electron transport chain). The electron transport chain produces the most energy and it involves the transfer of electrons through series of complex proteins.
As the electrons move through the individual complexes, energy is lost to form a proton gradient (H+). The proton gradient powers the synthesis of ATP from ADP as catalyzed by ATP synthase.