The correct option is B Eutrophication
Eutrophication is the ecosystem's response to the addition of artificial or natural nutrients, mainly phosphates, through detergents, fertilizers, or sewage, to an aquatic system. Eutrophication arises from the oversupply of nutrients, which induces explosive growth of plants and algae which, when such organisms die, they consume the oxygen in the body of water, thereby creating the state of hypoxia.