Assertion (A) : Carbon dioxide is one of the important greenhouse gases.
Reson (R) : It is largely produced by respiratory function of animals and plants.

Options

A. Both A and R are correct and R is the correct explanation of A
B. Both A and R are correct and R is not the correct explanation of A
C. Both A and R are not correct
D. A is not correct but R is correct

Explanation

### Step-by-Step Solution

1. **Understanding the Assertion**: The assertion states that "Carbon dioxide is one of the important greenhouse gases." We need to evaluate if this statement is true.

2. **Defining Greenhouse Gases**: Greenhouse gases are defined as gases that trap heat in the Earth's atmosphere. This is crucial for maintaining the Earth's temperature and supporting life.

3. **Identifying Prominent Greenhouse Gases**: Common greenhouse gases include carbon dioxide (CO2), methane (CH4), and ozone (O3). Since carbon dioxide is listed among these gases, we can conclude that the assertion is correct.

4. **Understanding the Reason**: The reason provided is that "It is largely produced by the respiratory function of animals and plants." We need to evaluate if this statement is true and whether it correctly explains why carbon dioxide is a greenhouse gas.

5. **Evaluating the Reason**: While it is true that animals and plants produce carbon dioxide during respiration, this is not the primary reason why carbon dioxide is considered a greenhouse gas. The major source of carbon dioxide emissions comes from human activities, particularly the burning of fossil fuels and industrial processes.

6. **Conclusion**: The assertion is correct, as carbon dioxide is indeed an important greenhouse gas. However, the reason provided does not accurately explain why carbon dioxide is classified as a greenhouse gas. Therefore, while both the assertion and reason are true, the reason does not serve as the correct explanation for the assertion.

7. **Final Answer**: The correct answer is that both the assertion and reason are correct, but the reason is not the correct explanation of the assertion.