With reference to Eutrophication, which of the following statements is/are correct?1.It is a phenomenon of nutrient enrichment of a water body.2.It depletes dissolved oxygen of the water.Select the correct answer using the codes given below:

1. A

   1 only

   Statement 1 is correct: eutrophication is nutrient enrichment of a water body, typically by nitrogen and phosphorus. But statement 2 is also correct, so ‘1 only’ is incomplete.

2. B

   2 only

   Statement 2 is correct: algal bloom and subsequent decay deplete dissolved oxygen (hypoxia). Statement 1 is also correct, so ‘2 only’ is wrong.

3. C

   Both 1 and 2

   Both statements are correct. Nutrient enrichment (especially N and P) causes algal bloom; death and bacterial decay of the bloom consume dissolved oxygen and can create dead zones. That is why (c) is the official key.

4. D

   Neither 1 nor 2

   Neither is false; both describe the same process, so (d) is wrong.

Summary. Official key is (c). Eutrophication is nutrient enrichment of water and it lowers dissolved oxygen after bloom and decay. Both 1 and 2 stand.