Here's why:

* Aerobic respiration literally means "with oxygen."

* Oxygen acts as the final electron acceptor in the electron transport chain, the final stage of aerobic respiration.

* This process generates a large amount of ATP (adenosine triphosphate), the primary energy currency of cells.

While glucose is the primary fuel source for aerobic respiration, oxygen is the essential molecule that allows the process to occur efficiently and produce the most energy.