The two gases making highest relative contribution to the greenhouse gases are:

Options

A. `CO_(2)` and `N_(2)O`
B. `CO_(2)` & `CH_(4)`
C. `CH_(4)` & `N_(2)O`
D. `CFC_(5)` & `N_(2)O`

Answer

To answer the question regarding the two gases making the highest relative contribution to greenhouse gases, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Greenhouse Gases**:
- Greenhouse gases are those gases that trap heat in the atmosphere, contributing to the greenhouse effect. They prevent heat from escaping back into space, leading to an increase in Earth's temperature.

2. **Identify Common Greenhouse Gases**:
- The main greenhouse gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons (CFCs).

3. **Analyze Contribution Percentages**:
- According to the information provided:
- Carbon dioxide (CO2) contributes approximately 60% to the greenhouse gases.
- Methane (CH4) contributes about 20%.
- Nitrous oxide (N2O) contributes around 6%.
- Chlorofluorocarbons (CFCs) contribute about 14%.

4. **Determine the Highest Contributors**:
- From the percentages, it is clear that carbon dioxide (CO2) and methane (CH4) are the two gases with the highest contributions to the greenhouse effect.

5. **Review the Options**:
- The options provided are:
- CO2 and N2O
- CO2 and CH4
- CH4 and N2O
- CFCs and N2O
- Based on our analysis, the correct option is CO2 and CH4.

6. **Conclude the Answer**:
- Therefore, the two gases making the highest relative contribution to greenhouse gases are **carbon dioxide (CO2) and methane (CH4)**.

### Final Answer:
The two gases making the highest relative contribution to the greenhouse gases are **carbon dioxide (CO2) and methane (CH4)**.

---