Yes because ATP is formed in electron transport chain from NADH and FADH2.

The correct answer is option 'D', the electron transport chain. In this stage of glucose oxidation, the greatest number of ATP molecules is formed from ADP. Let's explore the process in more detail:

Electron Transport Chain:
The electron transport chain is the final stage of glucose oxidation and occurs in the mitochondria. It involves the transfer of electrons from electron carriers, such as NADH and FADH2, to a series of protein complexes embedded in the mitochondrial inner membrane.

ATP Synthesis:
During the electron transport chain, the electron carriers donate their electrons to the protein complexes, which are responsible for pumping protons (H+) from the mitochondrial matrix to the intermembrane space. This creates a proton gradient across the inner membrane.

ATP synthase, an enzyme complex located in the inner mitochondrial membrane, utilizes this proton gradient to generate ATP. As protons flow back into the mitochondrial matrix through ATP synthase, the enzyme couples the movement of protons with the synthesis of ATP from ADP and inorganic phosphate (Pi) through a process called oxidative phosphorylation.

ATP Yield:
The electron transport chain produces a significant amount of ATP. For each NADH molecule oxidized, it contributes enough energy to produce approximately 2.5 to 3 ATP molecules. For each FADH2 molecule oxidized, it contributes enough energy to produce approximately 1.5 to 2 ATP molecules.

Since the electron transport chain receives electrons from multiple NADH and FADH2 molecules generated during previous stages of glucose oxidation (glycolysis, conversion of pyruvic acid to acetyl Co-A, and the Krebs cycle), it generates the largest number of ATP molecules from ADP. This is why the greatest number of ATP molecules is formed during the electron transport chain.

Summary:
During the complete oxidation of glucose, the electron transport chain is the final stage where the greatest number of ATP molecules is formed from ADP. This is because the electron transport chain utilizes the electron carriers generated in earlier stages to create a proton gradient, which is then used by ATP synthase to synthesize ATP through oxidative phosphorylation.