Every molecule of NADH fed into the ETC produces?

Explanation

The correct option is 3 ATP because each NADH molecule donates high-energy electrons to Complex I of the electron transport chain, initiating a series of redox reactions that pump protons across the inner mitochondrial membrane. This proton gradient drives ATP synthase to generate ATP from ADP and inorganic phosphate. The transfer of electrons from NADH to oxygen through the chain provides enough energy to produce about three molecules of ATP per NADH under classical bioenergetic calculations, making 3 ATP the most accurate value in this context.Option 2 ATP is incorrect because it underestimates the total energy yield from the complete transfer of electrons from NADH to oxygen.Option 4 ATP is incorrect because it overestimates the ATP yield beyond what the proton gradient can support.Option 6 ATP is incorrect because no single NADH molecule can produce that much energy in oxidative phosphorylation.