During aerobic respiration, what is the role of oxygen?
(a) Final CO₂ acceptor
(b) Final H acceptor   
(c) Driving force for withdrawal of H

Oxygen acts as the final hydrogen (H) acceptor during aerobic respiration. In the electron transport chain (ETC), electrons derived from NADH and FADH₂ are transferred through a series of protein complexes, and ultimately, oxygen serves as the final electron acceptor. It captures electrons and combines with protons (H⁺) to form water (H₂O). This process is known as the terminal step of oxidative phosphorylation, and it is crucial for generating a proton gradient and driving ATP synthesis.

Oxygen's role as the final hydrogen acceptor is essential in driving the withdrawal of hydrogen ions (H+) from the matrix to the intermembrane space of the mitochondria. As electrons flow through the ETC, protons are pumped out of the mitochondrial matrix, creating an electrochemical gradient.