Phosphate pollution is brought about by

Options

A. phosphate rocks
B. automobile exhausts
C. sewage and phosphate rocks
D. sewage and agricultural fertilisers.

Explanation

**Step-by-Step Solution:**

1. **Understanding Phosphate Pollution**: Phosphate pollution refers to the contamination of water bodies with phosphates, which can lead to various environmental issues, primarily eutrophication.

2. **Identifying Sources of Phosphate**: The main sources of phosphate pollution include:
- **Sewage Treatment Plants**: These facilities can discharge treated or untreated wastewater that contains phosphates.
- **Agricultural Fertilizers**: Phosphate fertilizers are widely used in agriculture to promote plant growth. When it rains, these fertilizers can wash off the fields and enter nearby water bodies.

3. **Mechanism of Pollution**: The runoff from agricultural fields and sewage treatment plants carries phosphates into rivers and lakes. This excess phosphate in the water can lead to:
- **Eutrophication**: This is a process where nutrient overload (especially phosphates) causes excessive growth of algae, known as algal blooms.
- **Algal Blooms**: These blooms can deplete oxygen in the water, harming aquatic life and disrupting ecosystems.

4. **Evaluating Options**: In the question, we are provided with several options regarding the sources of phosphate pollution:
- Option 1: Phosphate rock
- Option 2: Automobile exhaust
- Option 3: Sewage
- Option 4: Sewage and agricultural fertilizers

5. **Selecting the Correct Answer**: Among the options, the most accurate source of phosphate pollution is:
- **Sewage and agricultural fertilizers (Option 4)**. This is because both sewage and fertilizers contribute significantly to the phosphate levels in water bodies.

**Final Answer**: Phosphate pollution is brought about by sewage and agricultural fertilizers.

---