Answer:
c. transfer of electrons from cytochrome c to O2
Step-by-step explanation:
Actually in the electron transport chain cytochrome c oxidase is the final enzyme. From each 4 cytochrome c molecule It receives electron , transfer them dioxygen to form 2 molecules of water. 4 protons are used in order to make 2 water molecules and 4 protons are translocated across the membrane which create electrochemical potential.Hence electrochemical potential is generated and is utilized by ATP synthase to form ATP.
Hence answer is c. transfer of electrons from cytochrome c to O2.