Pollution responsible for causing phaeophyti-zation is

Options

A. `SO_(2)`
B. Nox
C. `CO_(2)`
D. Aeroallergens

Answer

### Step-by-Step Solution:

1. **Understanding Pollution**: Pollution is defined as any undesirable change in the environment that is harmful to living organisms and the ecosystem.

2. **Identifying Phaeophytization**: Phaeophytization refers to the process where chlorophyll in plants is degraded, leading to a loss of green color and the appearance of brown pigments. This process can affect aquatic plants and algae.

3. **Role of Sulfur Dioxide (SO2)**: One of the primary pollutants responsible for causing pheophytization is sulfur dioxide (SO2). This gas can be released into the atmosphere from various sources, including industrial processes and vehicle emissions.

4. **Mechanism of Action**: When sulfur dioxide is present in the environment, it can interact with chlorophyll in plants. The porphyrin ring, which is a crucial component of chlorophyll, can be distorted or destroyed by the action of SO2. This leads to the degradation of chlorophyll and the onset of pheophytization.

5. **Conclusion**: Therefore, the pollution responsible for causing pheophytization is sulfur dioxide (SO2).

### Final Answer:
The pollution responsible for causing pheophytization is sulfur dioxide (SO2).

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