Answer:
A. Runoff of artificial fertilizers
Explanation:
The excessive inclusion of nutrients in the water which adversely affects the life in the water bodies is known as eutrophication. The increase in the disposition of the effluents depletes the water bodies and decrease the oxygen content in the water. It is because of this reason that there is an increase in the production of biomass. The balance of the ocean ecosystem is effected adversely. Eutrophication is a major threat to the marine ecosystem.
