Here's a problem to solve: Fish breathe oxygen that is in the water where they swim. Which best describes the oxygen that fish breathe?

Among the 4 following options, which is the correct answer?

- A: The oxygen is a solution that dissolves the water.
 
- B: The oxygen is a substance that dissolves the water.
 
- C: The oxygen is a solute that is dissolved in the water.
 
- D: The oxygen is a solvent that is dissolved in the water.
 