The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is
A) oxidation of glucose to CO2 and water.
B) the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers.
C) the proton-motive force across the inner mitochondrial membrane.
D) the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.
E) the final transfer of electrons to oxygen.
Answer: C