BOD (Biochemical Oxygen Demand) is a measure of

AAir pollution

BWater contamination ✓ Correct

CSoil contamination

DDissolved oxygen of river water

Correct answer: (B) Water contamination

Explanation

Biochemical oxygen demand measures the oxygen microbes need to break down organic matter in water, indexing water contamination.

It is not a measure of air pollution.

It does not gauge soil contamination.

It measures oxygen demand, not the dissolved oxygen already present in river water.

A high value means heavy organic pollution and low water quality.

Sewage and untreated effluent raise the biochemical oxygen demand of a river.

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