The amount of dissolved oxygen in water may decrease because of the

decrease in density of water

increase in plants in the water

decrease in temperature of water

increase in organic matter in the water

Option D

Explanation:

Increase in organic matter in the water will lead to production of microbes, algae, and all other  water species  by feeding  on increased organic matter. This organic matter will act as  food for the species living under the water.

With increased food supply, the population of water species will also increase which in turn will consume more and more dissolved oxygen from water thereby making it devoid of oxygen.

Hence, option D is correct

they have sperm in my gf's mouth

explanation: