Question

Assertion (A): The problem of organic pollution in rivers is usually worse in the hot summer months.
Reason (R): Higher water temperatures exacerbate oxygen depletion.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A)
• B. Both (A) and (R) are true but (R) is not the correct explanation of (A)
• C. (A) is true but (R) is not correct
• D. (A) is false but (R) is correct

Hint:

Always verify if the reason directly explains the assertion — both must be individually true for Option (2), but the cause-effect link must be missing.

Answer 1

The Correct Option is B

Organic pollution in rivers increases in the summer because higher temperatures promote the growth of microorganisms that consume oxygen. While (R) is true — warmer water holds less dissolved oxygen, leading to oxygen depletion — it does not fully explain why organic pollution worsens. The increase in pollution is also due to increased biological activity and not just because of oxygen depletion. Hence, both statements are true, but (R) is not the correct explanation of (A).