Which sentence best describes the origin of the kinetic energy used to make
ATP from ADP and phosphate groups?

A. ADP molecules flow through ATP synthase and combine with
phosphate groups to form ATP molecules.

B. Electrons flow through ATP synthase after they pass through the
electron transport chains.

C. ATP synthase proteins flow through the inner membranes of
mitochondria and provide energy that is transferred to ATP.

D. Hydrogen ions (H+) that have built up on one side of the inner
membrane of a mitochondrion flow through ATP synthase.