Eutrophication is caused by

Options

A. Phosphate rocks only
B. Agricultural
C. fertilizers only Sewage and phosphate rocks
D. Sewage and agricultural fertilizers

Answer

**Step-by-Step Solution:**

1. **Understanding Eutrophication**: Eutrophication is a process characterized by the excessive enrichment of nutrients in water bodies, which leads to an increase in algae and plant growth.

2. **Identifying Causes**: The primary causes of eutrophication are:
- **Untreated Sewage**: When untreated sewage is discharged into water bodies, it introduces a high amount of organic matter, which increases nutrient levels. This process is referred to as organic loading.
- **Fertilizer Runoff**: Rainwater can wash fertilizers from agricultural fields into nearby water bodies. These fertilizers are rich in nitrogen and phosphorus, which further contribute to nutrient enrichment.

3. **Effects of Eutrophication**: The increase in nutrients leads to algal blooms, which can deplete oxygen in the water, harming aquatic life. This phenomenon can create a cycle of negative impacts on the ecosystem.

4. **Conclusion**: Based on the understanding of the causes of eutrophication, the correct answer to the question "Eutrophication is caused by" is the combination of untreated sewage and agricultural runoff containing fertilizers.

**Final Answer**: Eutrophication is caused by untreated sewage and agricultural runoff containing fertilizers.

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