Which of the following is not a natural source of pollution:

Options

A. Automobile
B. Earthquake
C. Floods
D. Volcanoes

Answer

To determine which of the following options is not a natural source of pollution, let's analyze some common sources of pollution:

1. **Automobiles**: These are man-made vehicles that emit pollutants into the air, such as carbon monoxide, nitrogen oxides, and particulate matter. Therefore, they are not a natural source of pollution.

2. **Floods**: Flooding is a natural event caused by excessive rainfall or melting snow. While floods can lead to pollution (e.g., by spreading contaminants), the floods themselves are a natural phenomenon.

3. **Volcanoes**: Volcanic eruptions are natural events that release ash, gases, and other pollutants into the atmosphere. Thus, they are considered a natural source of pollution.

4. **Tsunamis**: Tsunamis are large ocean waves caused by underwater earthquakes or volcanic eruptions. They can cause pollution by spreading debris and contaminants, but they are also a natural occurrence.

Based on this analysis, the option that is not a natural source of pollution is **Automobiles**.

### Step-by-Step Solution:

1. **Identify the sources of pollution**: List the options provided in the question.
2. **Classify each source**: Determine whether each source is natural or man-made.
3. **Analyze each option**:
- **Automobiles**: Man-made, not natural.
- **Floods**: Natural event.
- **Volcanoes**: Natural event.
- **Tsunamis**: Natural event.
4. **Conclude**: Identify the option that is not a natural source of pollution.