What is the cause of accelerated eutrophication ?

Increased amount of dissolved oxygen. Increased DDT and mercury concentration in water. Disposal of nitrate and phosphate rich waste in water . None of these.

Disposal of nitrate and phosphate rich waste in water .

Cultural or accelerated eutrophication is nutrient enrichment of water bodies due to human activities like passage of sewage, industrial effluents and runoff from fertilised fields rich in nitrates and phosphates. Nutrients present in sewage , agriculture wastes and fertilisers cause dense growth of plants and planktonic algae.