Which of the following is the use of lichens in case of pollution?

Options

A. Lichens are not related with pollution
B. They act as bioindicators of pollution
C. They treat the polluted water
D. They promote pollution

Explanation

### Step-by-Step Solution:

1. **Understanding Lichens**: Lichens are symbiotic organisms made up of fungi and algae or cyanobacteria. They are known for their sensitivity to environmental changes, particularly pollution.

2. **Definition of Bioindicators**: Bioindicators are organisms that can provide information about the health of an environment. They respond to changes in environmental conditions, such as pollution levels.

3. **Sensitivity to Pollution**: Lichens are particularly sensitive to air pollutants, especially sulfur dioxide. They cannot thrive in areas with high levels of air pollution, which makes them useful for monitoring air quality.

4. **Role in Pollution Monitoring**: Because lichens are sensitive to pollutants, their presence or absence can indicate the level of air pollution in a given area. They can also accumulate toxic elements, making them effective bioindicators.

5. **Evaluating the Options**:
- **Option 1**: "Lichens are not related to pollution." - This is incorrect.
- **Option 2**: "They act as bioindicators of pollution." - This is correct.
- **Option 3**: "They treat the polluted water." - This is incorrect.
- **Option 4**: "They promote pollution." - This is incorrect.

6. **Conclusion**: The correct answer is that lichens act as bioindicators of pollution.