Which statement best describes the function of atp synthase?

atp synthase pumps protons back into the mitochondrial matrix.
atp synthase utilizes energy of the proton gradient to attach phosphate groups to adp.
atp synthase shuttles high-energy electrons to synthesize atp.
atp synthase produces reduced coenzymes nadh and fadh2.

ATP synthase utilizes energy of the proton gradient to attach phosphate groups to ADP.

Explanation:

ATP synthase is an enzyme that requires some form of energy to form energy storing molecule ATP, from adenosine diphosphate (ADP) and inorganic phosphate (Pi). Because of that, ATP synthesis is coupled with cellular respiration and electrochemical gradient created by the difference in proton (H+) concentration across the mitochondrial membrane during the transport of electrons through the electron transport chain. In plants, proton gradient is formed in chloroplast, in the thylakoid lumen through the thylakoid membrane.

we would need to see the picture to answer it