The Free-Energy Change for the Oxidation of Glucose to CO₂

The free-energy change for the oxidation of glucose to CO₂ and water is -686 kcal/mol,and the free-energy change for the reduction of NAD⁺ to NADH is +53 kcal/mol.Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?

A) Most of the-free energy available from the oxidation of glucose is captured by the production of ATP.
B) Glycolysis is a very inefficient process,with much of the energy from glucose released as heat.
C) Most of the free energy available from the oxidation of glucose remains in pyruvate,one of the products of glycolysis.
D) Glycolysis consists of many enzyme-catalyzed reactions,each of which extracts a small amount of energy from the glucose molecule.