Which of the following pairs is a major contributor to global warming?

Options

A. carbon dioxide and oxides of nitrogen
B. methane and water vapour
C. carbon dioxide and ozone
D. carbon dioxide and water vapour

Explanation

To solve the question "Which of the following pairs is a major contributor to global warming?", we will analyze the options provided and identify the gases that significantly contribute to the phenomenon of global warming.

### Step-by-Step Solution:

1. **Understanding Global Warming**:
- Global warming refers to the increase in Earth's average temperature due to the greenhouse effect, where certain gases in the atmosphere trap heat from the sun.

2. **Identifying Greenhouse Gases**:
- The primary greenhouse gases that contribute to global warming include:
- Carbon dioxide (CO2)
- Methane (CH4)
- Water vapor (H2O)
- Ozone (O3)

3. **Analyzing Each Option**:
- **Option 1: Carbon dioxide and oxides of nitrogen**:
- Carbon dioxide is a major contributor to global warming, but oxides of nitrogen (NO, NO2) primarily cause air pollution and acid rain, not significant global warming.
- **Option 2: Methane**:
- Methane is a potent greenhouse gas, but the option does not pair it with another significant contributor.
- **Option 3: Carbon dioxide and ozone**:
- Carbon dioxide contributes to global warming, but ozone primarily protects the Earth from ultraviolet rays and does not significantly contribute to global warming.
- **Option 4: Carbon dioxide and water vapor**:
- Both carbon dioxide and water vapor are significant contributors to global warming. Carbon dioxide traps heat effectively, and water vapor amplifies the greenhouse effect by holding more heat.

4. **Conclusion**:
- After analyzing all options, the pair that is a major contributor to global warming is **Option 4: Carbon dioxide and water vapor**.

### Final Answer:
**The correct answer is Option 4: Carbon dioxide and water vapor.**