Answer:
C. toxic substances in the water
Explanation:
Cultural eutrophication refers to the release of excessive nutrients in form of sewage, fertilizer, etc. into the water body from a human source or as a result of anthropogenic/human activities. This, however, negatively affects the composition of the water body.
Generally, eutrophication causes the proliferated growth of algae in the water called ALGAL BLOOM because they utilize these waste materials as nutrient source. An uncontrolled increase in growth of algae can induce the release of harmful toxins into the water body, thereby, causing the death of aquatic organisms like fishes.
