The smog is essentially caused by the presence of

Options

A. `O_2` and `O_3`
B. `O_2` and `N_2`
C. Oxides of sulphur and nitrogen
D. `O_3` and `N_2`

Answer

### Step-by-Step Solution:

1. **Understanding Smog**: Smog is a type of air pollution that is characterized by a mixture of smoke and fog. It typically occurs in urban areas and can be harmful to health.

2. **Identifying Causes**: The primary components that contribute to the formation of smog are pollutants released into the atmosphere. These pollutants include various gases and particulate matter.

3. **Key Pollutants**: The main pollutants responsible for smog formation are:
- **Oxides of Sulfur (SOx)**: These are produced from the burning of fossil fuels, especially in power plants and industrial processes.
- **Nitrogen Oxides (NOx)**: These are primarily emitted from vehicles and industrial activities.

4. **Role of Fuels**: When fuels such as gasoline and diesel are burned, they release these oxides into the atmosphere. This process occurs during combustion in vehicles and industrial plants.

5. **Chemical Reactions**: In the presence of sunlight and heat, these gases can undergo chemical reactions, leading to the formation of fine particulate matter and other secondary pollutants that contribute to smog.

6. **Conclusion**: Therefore, the presence of oxides of sulfur and nitrogen, along with particulate matter from combustion processes, is essentially what causes smog.

### Final Answer:
The smog is essentially caused by the presence of oxides of sulfur (SOx) and nitrogen (NOx) released from burning fuels in vehicles and industrial activities.

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