All Animals Need Oxygen Gas (O2)for Their Primary Cellular-Level Functioning

All animals need oxygen gas (O2) for their primary cellular-level functioning. Inside the cell, O2 is split apart into oxygen atoms. Eventually, electrons that are flowing through the cell will be "received" by this oxygen. But first, the electrons combine with protons present in the cell to form a basic element that has a single proton and a single electron. Then, this element combines with the oxygen to form a certain chemical compound. In this scenario, what chemical compound is produced?

A) water (H2O)
B) carbon dioxide (CO2)
C) ozone (O3)
D) bicarbonate (HCO3)