The correct option is D oxidative phosphorylation
During the complete oxidation of glucose, the highest number of ATP molecules are formed during the oxidative phosphorylation. During oxidative phosphorylation, 34 molecules of ATP are produced.
Aerobic respiration involves glycolysis, link reaction (oxidative decarboxylation of pyruvate), Krebs cycle, electron transport chain and oxidative phosphorylation.
During glycolysis, there is a net gain of 2 molecules of ATP.
During the Krebs cycle, 2 ATP molecules are produced.
During conversion of pyruvate to Acetyl coA, there is no synthesis of ATP.
During electron transport chain, NADH+H+ and FADH2 formed during glycolysis, oxidative decarboxylation and Krebs cycle undergo oxidation and release electrons. These energy rich electrons are utilised to synthesise ATP. A total of 10 molecules of NADH+H+ and 2 molecules of FADH2 are produced during various pathways of aerobic respiration.
Oxidation of one molecule of NADH yields 3 ATP and oxidation of one molecule of FADH2 yields 2 ATP. Hence, a total of 34 ATP are generated during oxidative phosphorylation.