Eutrophication occurs because of :

Options

A. Calcium and Magnesium
B. Nitrogen and phosphorus
C. Carbon and oxygen
D. Mercury and DDT

Answer

**Step-by-Step Solution:**

1. **Understanding Eutrophication**:
- Eutrophication is defined as the enrichment of water bodies with nutrients, leading to changes in the ecosystem.

2. **Identifying Nutrient Sources**:
- The primary nutrients responsible for eutrophication are nitrogen and phosphorus. These nutrients often come from agricultural fertilizers and pesticides.

3. **Effects of Eutrophication**:
- The excessive nutrients lead to an overgrowth of algae (algal bloom) and aquatic plants. This growth can deplete oxygen levels in the water, harming aquatic life, particularly fish.

4. **Analyzing the Options**:
- We need to evaluate the provided options to identify which one correctly identifies the cause of eutrophication.
- Option 1: Calcium and magnesium - Incorrect, as these do not primarily cause eutrophication.
- Option 2: Nitrogen and phosphorus - Correct, as these are the main contributors to eutrophication.
- Option 3: Mercury and DDT - Incorrect, as these are associated with bio-magnification rather than eutrophication.

5. **Conclusion**:
- Based on the analysis, the correct answer is **Nitrogen and phosphorus** (Option 2) as they are the key nutrients that lead to eutrophication.

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