Which of the following is not a natural source of air pollution ?

Options

A. Volcanic eruptions
B. Forest fires
C. Dust storms
D. Photochemical smog

Answer

To determine which of the following is not a natural source of air pollution, we need to analyze the options provided.

### Step-by-Step Solution:

1. **Identify Natural Sources of Air Pollution**:
- Natural sources of air pollution include phenomena such as volcanic eruptions, wildfires, dust storms, and natural decay of organic matter.

2. **Consider the Options**:
- Let's assume the options provided are:
a) Volcanic eruptions
b) Wildfires
c) Industrial emissions
d) Dust storms

3. **Analyze Each Option**:
- **Volcanic eruptions**: These are natural events that release gases and ash into the atmosphere, contributing to air pollution.
- **Wildfires**: These are also natural occurrences that can produce smoke and particulate matter, leading to air pollution.
- **Industrial emissions**: These are caused by human activities, specifically from factories and power plants, and are not natural sources.
- **Dust storms**: These are natural events that can lift dust and particulate matter into the air, contributing to pollution.

4. **Conclusion**:
- Among the options, **industrial emissions** are not a natural source of air pollution. They are a result of human activities.

### Final Answer:
**Industrial emissions** are not a natural source of air pollution.

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