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Sewage drained into water bodies kill fishes because
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- excessive carbon dioxide is added to water
- it gives off a bad smell
- it removes the food eaten by fish
- it increases competition with fishes for dissolved oxygen
Correct Option: D
Organic pollutants brought in by the sewage drained into water bodies provides nutrients for stimulating growth of algae. Algal bloom reduces availability of light to the submerged plants which get killed. Dead algae and dead submerged plants consume oxygen during decomposition, causing oxygen depletion and increases competition for oxygen.
