All the following contribute to pollution except

Options

A. Thermal power plant
B. Automobiles
C. Nuclear power plant
D. Hydroelectric power project

Answer

**Step-by-Step Solution:**

1. **Understanding Pollution**: Begin by defining pollution. Pollution refers to any undesirable change in the physical, chemical, and biological characteristics of air, land, water, or soil.

2. **Identifying the Options**: The question provides four options: thermal power plant, automobiles, nuclear power plant, and hydroelectric power plant. We need to determine which of these does not contribute to pollution.

3. **Analyzing Each Option**:
- **Thermal Power Plant**: These plants generate electricity by burning fossil fuels, which releases pollutants into the air, including particulate matter and gases. Thus, they contribute to pollution.
- **Automobiles**: Vehicles emit exhaust gases and particulate matter, making them a significant source of air pollution, especially in urban areas. Therefore, they contribute to pollution.
- **Nuclear Power Plant**: While nuclear power plants do not emit greenhouse gases during operation, they can produce radioactive waste and other pollutants. However, their overall contribution to air pollution is lower compared to thermal power plants and automobiles.
- **Hydroelectric Power Plant**: These plants generate electricity by harnessing the energy of flowing water. They do not produce air pollutants or contribute to air pollution in the same way as the other options. Thus, they are considered environmentally friendly.

4. **Conclusion**: Based on the analysis, the hydroelectric power plant is the only option that does not contribute to pollution. Therefore, the correct answer is the hydroelectric power plant.

**Final Answer**: Hydroelectric power plant (Option 4) does not contribute to pollution.

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