Correct Option: D

The enzyme responsible for oxidative phosphorylation is ATP synthase. ATP synthase is located in the F₁ component of F₀ – F₁ or elementary particles. ATP synthase becomes active in ATP formation only where there is a proton gradient having higher concentration of H⁺ or protons on the F₀ side as compared to F₁ side. Increased proton concentration is produced in the outer chamber of outer surface of inner mitochondrial memberane by the pushing of protons with the help of energy liberated by passage of electrons from one carrier to another.