Which one of the following forms of energy leads to least environmental pollution in the process of its harnessing and utilisation ?

Options

A. Nuclear energy
B. Thermal energy
C. Solar energy
D. Geothermal energy

Explanation

To determine which form of energy leads to the least environmental pollution during its harnessing and utilization, we can analyze the options provided: nuclear, thermal, solar, and geothermal energy.

### Step-by-Step Solution:

1. **Understanding the Energy Sources**:
- **Nuclear Energy**: This energy is generated through nuclear reactions, typically fission. While it produces a significant amount of energy, it generates radioactive waste, which poses environmental hazards and requires careful management.
- **Thermal Energy**: This energy is produced by burning fossil fuels such as coal, oil, or natural gas. The combustion process releases greenhouse gases and other pollutants into the atmosphere, contributing to air pollution and climate change.
- **Geothermal Energy**: This energy is derived from the heat stored beneath the Earth's surface. While it is cleaner than fossil fuels, the process of harnessing geothermal energy can lead to land degradation and the release of greenhouse gases.
- **Solar Energy**: Solar energy is harnessed from sunlight using solar panels. This process does not produce emissions during operation, and it has minimal environmental impact compared to the other energy sources.

2. **Evaluating Environmental Impact**:
- **Nuclear Energy**: High environmental risk due to radioactive waste.
- **Thermal Energy**: Significant pollution from burning fossil fuels.
- **Geothermal Energy**: Moderate environmental concerns, mainly related to land use and emissions.
- **Solar Energy**: Very low environmental impact; no emissions during operation.

3. **Conclusion**:
Based on the analysis, solar energy leads to the least environmental pollution during its harnessing and utilization. It is a clean, renewable resource that does not emit harmful pollutants.

### Final Answer:
**Solar Energy**

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