Aquatic animals use dissolved oxygen to breathe but how the oxygen enters the water bodies?

(i) Through diffusion from the atmosphere.

(ii) From aquatic plants.

(iii) From aquatic animals only.

(iv) By water cycle.

Aquatic animals consume dissolve oxygen. This oxygen is available in water by two processes-

1. Diffusion from the atmosphere: When air comes in contact with water bodies, the oxygen is diffused from higher concentrations to lower concentrations.
2. Aquatic plants: Aquatic plants also consume carbon dioxide (produced by aquatic animals) and produce oxygen gas which becomes dissolved in water.

Thus, statements (i) and (ii) are correct