Which of the following is a source of energy but does not cause pollution ?

Options

A. Sun
B. water
C. gasoline
D. fossil fuel

Answer

To determine which of the following options is a source of energy that does not cause pollution, we will analyze each option provided:

1. **Sun**: The sun is a natural source of energy that provides solar energy. It does not produce any pollutants when harnessed for energy. Solar panels convert sunlight into electricity without emitting harmful substances. Therefore, the sun is a source of energy that does not cause pollution.

2. **Water**: Water can be used to generate energy through hydroelectric power. This process involves the movement of water to turn turbines, generating electricity. While the construction of dams can have environmental impacts, the process of generating energy from flowing water itself does not produce pollution. Thus, water is also a source of energy that does not cause pollution.

3. **Gasoline**: Gasoline is a fossil fuel used primarily in internal combustion engines. When burned, it releases various pollutants, including carbon monoxide, nitrogen oxides, and unburned hydrocarbons, contributing to air pollution. Therefore, gasoline is not a suitable option as it causes pollution.

4. **Fossil Fuels**: Similar to gasoline, fossil fuels (such as coal, oil, and natural gas) release harmful emissions when burned. These emissions contribute to air pollution, acid rain, and other environmental issues. Therefore, fossil fuels are also not a source of energy that is free from pollution.

Based on this analysis, the correct answers are:
- **Sun**
- **Water**

### Step-by-Step Solution:
1. **Identify the options**: Sun, Water, Gasoline, Fossil Fuels.
2. **Analyze each option**:
- **Sun**: No pollution when harnessed for energy.
- **Water**: No pollution during energy generation (hydroelectric).
- **Gasoline**: Causes pollution when burned.
- **Fossil Fuels**: Causes pollution when burned.
3. **Conclude**: The sources of energy that do not cause pollution are the Sun and Water.