It is advised to put oil on stagnant water to prevent breeding of mosquitoes. This is because

Options

A. (a)all cuts off oxygen supply, thereby stops the breeding of mosquitoes
B. (b)mosquitoes are repelled by oil
C. (c)mosquitoes are killed by oil
D. (d)mosquitoes get stuck In the layer of oil

Answer

To answer the question, "It is advised to put oil on stagnant water to prevent breeding of mosquitoes. This is because," we will analyze the reasoning behind this practice step by step.

### Step-by-Step Solution:

1. **Understanding Stagnant Water**:
- Stagnant water refers to water that is not flowing and has been sitting in one place for an extended period. This type of water is often a breeding ground for mosquitoes, as they lay their eggs in it.

2. **Role of Oil**:
- When oil is added to stagnant water, it forms a thin layer on the surface. This layer of oil has several effects on the water below.

3. **Cutting Off Oxygen Supply**:
- The oil layer prevents oxygen from dissolving in the water and also blocks the access of mosquito larvae to the surface. Mosquito larvae, which need to breathe air, cannot reach the surface due to the oil layer.

4. **Impact on Mosquito Breeding**:
- As a result of the lack of oxygen, the larvae cannot survive, leading to a decrease in the mosquito population. This effectively stops the breeding process.

5. **Conclusion**:
- Therefore, the correct reason for putting oil on stagnant water to prevent the breeding of mosquitoes is that it cuts off the oxygen supply, thereby stopping the breeding of mosquitoes.

### Final Answer:
The correct answer is: "It cuts off the oxygen supply thereby stops the breeding of mosquitoes."

---