In earthworm, `CO_(2)` diffuses out to surrounding atmosphere through

Options

A. Spiracles
B. Nephridiopores
C. Body surface
D. Setae

Explanation

To answer the question "In earthworm, CO₂ diffuses out to the surrounding atmosphere through," we will analyze the options provided and determine the correct one step by step.

### Step-by-Step Solution:

1. **Understanding the Options**:
- The options given are:
- A) Spiracles
- B) Nephridiopores
- C) Body surface
- D) Ctenidia (seething)

2. **Analyzing Spiracles**:
- Spiracles are openings associated with the tracheal system, primarily found in insects like cockroaches.
- **Conclusion**: Spiracles are not present in earthworms. Thus, this option is incorrect.

3. **Analyzing Nephridiopores**:
- Nephridiopores are openings related to the excretory system in earthworms.
- They are responsible for the excretion of waste materials but are not involved in gas exchange.
- **Conclusion**: Since they are not involved in gas exchange, this option is also incorrect.

4. **Analyzing Body Surface**:
- Earthworms perform cutaneous respiration, which means they exchange gases directly through their skin (body surface).
- The skin of earthworms is moist, allowing for the diffusion of gases (oxygen and carbon dioxide) based on the difference in their partial pressures between the body and the surrounding atmosphere.
- **Conclusion**: This is the correct mechanism for gas exchange in earthworms.

5. **Analyzing Ctenidia (Seething)**:
- Ctenidia are structures found in some aquatic animals, primarily for respiration and are not related to earthworms.
- **Conclusion**: This option is also incorrect.

6. **Final Answer**:
- After analyzing all the options, we conclude that the correct answer is:
- **C) Body surface**