The region which is greatly affected by air pollution is

Options

A. troposphere
B. stratosphere
C. mesosphere
D. thermosphere.

Explanation

### Step-by-Step Solution:

1. **Identify the Layers of the Earth**:
- The Earth has several layers, including the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
- The troposphere is the lowest layer, extending from the Earth's surface up to about 12 kilometers.

2. **Understand the Impact of Air Pollution**:
- Air pollution primarily affects the troposphere because it is the layer where most human activities occur.
- This includes industrial activities, transportation, and other processes that release pollutants into the air.

3. **Explain Why the Troposphere is Affected**:
- The troposphere is where weather phenomena occur, including cloud formation.
- Pollutants such as gases and solid particles accumulate in this layer, leading to air quality issues.

4. **List Common Pollutants**:
- Common air pollutants found in the troposphere include:
- Oxides of sulfur (SOx)
- Carbon dioxide (CO2)
- Dust and fumes from vehicles and industries

5. **Conclude the Answer**:
- Given that the troposphere is the layer of the atmosphere most affected by air pollution, the answer to the question is the troposphere.

### Final Answer:
The region which is greatly affected by air pollution is the **troposphere**.

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