Which of the Following Is Most Directly Responsible for Driving

Which of the following is most directly responsible for driving ATP synthase and the production of ATP in cellular respiration?

A) The electron transport chain pumping H⁺ from the mitochondrial matrix into the intermembrane space.
B) The flow of electrons down the electron transport chain.
C) The loss in free energy that occurs as an electron moves down the transport chain.
D) The H⁺ electrochemical gradient across the inner mitochondria membrane.
E) The ability of oxygen to rapidly capture an electron and energize ATP synthase.