The oxygen is a solution that dissolves the water. The oxygen is a substance that dissolves the water. The oxygen is a solute that is dissolved in the water. The oxygen is a solvent that is dissolved in the water.
I gave my students this multiple choice question: Fish breathe oxygen that is in the water where they swim. Which best describes the oxygen that fish breathe?

Only one answer is correct among these 4 choices:
- The oxygen is a solution that dissolves the water.
- The oxygen is a substance that dissolves the water.
- The oxygen is a solute that is dissolved in the water.
- The oxygen is a solvent that is dissolved in the water.

Could you tell me which one is correct?

The oxygen is a solute that is dissolved in the water.