Answer:
A. humans going underwater and exhaling
Explanation:
The dissolved oxygen in water refers to the amount of oxygen that is found in water. However, there are various ways that oxygen dissolves in a body of water, these includes;
- Photosynthesis of aquatic plants: Oxygen is the waste product of the photosynthetic process carried out by green plants. Hence, when aquatic plants undergo photosynthesis, oxygen from them tend to dissolve into water.
- Diffusion from the atmosphere: Oxygen from air or atmosphere also dissolves in water
- aeration as water moves over rocks and debris, and from wind and waves
However, humans do not exhale oxygen but carbon dioxide, hence, it is not a source of dissolved oxygen
