Answer:
C. Excess nutrients promote the growth of algae
Step-by-step explanation:
The eutrophication can simply be explained as an over-saturation of the waters with nutrients. This usually happens because of the human activity, with the largest sources that contribute to this being the fecal matter from the farmed animals and the fertilizers used in the agriculture. They are either released into the water directly or manage to reach it on their own by natural means. Once they reach the water they increase the amount of nutrients a lot, and that prompts the growth of the algae. As the algae grow more and more and occupy more and more area, they block the sunlight, so the organisms that use photosynthesis die out. Also, the algae contribute to eliminating the oxygen of the waters, so the fish and the other organisms die out as well, leading to a total collapse of the ecosystem.