Greenhouse gases are

Options

A. `CO_2`
B. `CH_4`
C. `SO_2`
D. `CFC`

Answer

### Step-by-Step Solution:

1. **Understanding Greenhouse Gases**: Greenhouse gases are gases in the Earth's atmosphere that trap heat. They allow sunlight to enter but prevent some of the heat that the sunlight brings from leaving the atmosphere.

2. **Identifying Common Greenhouse Gases**: The most common greenhouse gases include:
- Carbon Dioxide (CO2)
- Methane (CH4)
- Water Vapor
- Ozone (O3)
- Nitrous Oxide (N2O)
- Sulfur Dioxide (SO2)
- Chlorofluorocarbons (CFCs)

3. **Listing the Greenhouse Gases**: Based on the information provided, we can list the greenhouse gases mentioned:
- CO2 (Carbon Dioxide)
- CH4 (Methane)
- SO2 (Sulfur Dioxide)
- CFC (Chlorofluorocarbons)
- Water Vapor
- Ozone
- N2O (Nitrous Oxide)

4. **Conclusion**: Since all the gases mentioned (CO2, CH4, SO2, CFC) are greenhouse gases, the answer to the question "What are greenhouse gases?" is that all the options provided are correct.

### Final Answer:
All of the gases listed (CO2, CH4, SO2, CFC) are greenhouse gases.

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