Sewage drained into water bodies kill fishes because

Options

A. excessive carbon dioxide is added to water
B. it gives off a bad smell
C. it removes the food eaten by fish
D. it increases competition with fishes for dissolved oxygen

Answer

D

Explanation

Sewage provides food for decomposers. Phosphorus and nitrogen compounds present in sewage result into excessive growth of algae on water surface, which is also called algal bloom, this all result in decrease in oxygen, which is dangerous for quatic life.