The role of oxygen in the release of energy from food primarily relates to its role in cellular respiration. In this process, oxygen is used to help break down fuel molecules (like glucose) to release stored energy. Therefore, the correct response is:
Oxygen causes fuel molecules to break apart.
In the presence of oxygen, cells can efficiently convert glucose and other nutrients into energy (ATP) through processes such as aerobic respiration, which involves breaking down these molecules to release energy.