Which statement about oxygen is true?

• A. It is not used by the human body.
• B. Oxygen participates in photosynthesis in plants.
• C. Oxygen supports the process of combustion.
• D. It cannot be delivered by medical devices.

Answer: (C)

Oxygen’s role as the oxidizer in combustion is what makes this statement the correct one. Combustion requires a substance that accepts electrons from the fuel in the presence of heat, and oxygen is the most common oxidizer in our environment, so it enables flames to burn.

The other ideas don’t fit as well. Humans rely on oxygen for cellular respiration to release energy from nutrients, so saying it isn’t used by the body is inaccurate. In photosynthesis, plants produce oxygen as a byproduct rather than consuming it, so oxygen doesn’t participate as a reactant in that process. And oxygen can indeed be delivered medically through devices like oxygen tanks or concentrators, so that claim is false.