Which statement describes the generation of the proton motive force used by ATP synthase?

• A. The proton gradient is formed when protons are pumped across the inner mitochondrial membrane by the electron transport chain, creating a gradient used by ATP synthase.
• B. The proton gradient is formed by ATP hydrolysis pumping protons across the membrane; gradient drives glycolysis.
• C. The proton gradient is created by substrate-level phosphorylation in the cytosol.
• D. The proton gradient is not involved in ATP production.

Answer: (A)