Which of these can help reduce air pollution?

Options

A. Air conditioners
B. Electrostatic precipitators
C. Thermal power plants
D. Grass fires

Explanation

### Step-by-Step Solution:

1. **Understanding Air Pollution**:
- Air pollution refers to the presence of harmful substances in the air, which can be in excess and detrimental to health and the environment.

2. **Analyzing the Options**:
- **Air Conditioners**: Older models can leak CFCs (chlorofluorocarbons), which contribute to ozone layer depletion rather than reducing air pollution.
- **Electrostatic Precipitators**: These devices are used in industrial settings to capture and remove pollutants like dust and smoke from the air, thus helping to reduce air pollution.
- **Thermal Power Plants**: They burn fossil fuels, which release carbon dioxide and other pollutants into the atmosphere, contributing to air pollution.
- **Grass Fires**: Similar to thermal power plants, grass fires release carbon dioxide and other harmful substances, worsening air pollution.

3. **Identifying the Best Option**:
- Among the four options, the **Electrostatic Precipitator** is the only one that actively helps to reduce air pollution by capturing pollutants before they can enter the atmosphere.

4. **Conclusion**:
- Therefore, the correct answer is **Electrostatic Precipitators**.