Answer:
H2O (Water)
Step-by-step explanation:
Oxygen (O2) is the final acceptor molecule after the process of aerobic respiration. Specifically, it accepts hydrogen ions at the end of the electron transport chain, the main energy-generating stage of cellular respiration.
This is why oxygen is needed to form large amounts of cellular energy, as without it, the electron transport chain cannot proceed. When oxygen accepts hydrogen ions, it forms water, a byproduct of aerobic respiration.