Which statement about oxygen is correct?

• A. Oxygen supports the process of combustion.
• B. It is used only by plants in photosynthesis.
• C. It cannot be delivered to patients as supplemental therapy.
• D. It has no role in respiration.

Answer: (A)

Oxygen’s role as the oxidizer that drives combustion is what this item is testing. Combustion is a reaction where a fuel reacts with an oxidizer, releasing heat and often light. Oxygen is the most common oxidizer in fires, and having more oxygen available makes the oxidation process occur more rapidly, so flames burn hotter and more vigorously. That’s why the statement describing oxygen as supporting combustion is correct. In medical contexts, supplemental oxygen is routinely given to patients to increase blood oxygen levels, illustrating oxygen’s essential role in respiration and energy production at the cellular level. The other statements aren’t accurate: oxygen isn’t used only by plants in photosynthesis, it can be and is delivered as supplemental therapy, and it does play a crucial role in respiration.