20. The electron transport chain (ETC) is one part in oxidative phosphorylation, which is the last step in cellular respiration. Which of the following is true?

a. The movement of electrons down the ETC drives the formation of a proton gradient.
b. The movement of H+ ions across the inner membrane of the mitochondria drives the transfer of electrons down the
ETC
c. The movement of H+ ions through ATP synthase drives the transfer of electrons down the ETC
d. The movement of electrons down the ETC drives the movement of ADP and phosphate through ATP synthase.