Air sacs are found only inn

Options

A. Aquatic birds
B. Ground birds
C. All birds
D. No bird

Answer

**Step-by-Step Solution:**

1. **Understanding Air Sacs**:
- Air sacs are specialized structures that are extensions of the lungs. They play a crucial role in respiration by allowing for a more efficient exchange of gases.

2. **Identifying Organisms with Air Sacs**:
- Air sacs are primarily found in birds. They are integral to the bird's respiratory system, allowing for a continuous flow of air through the lungs.
- Additionally, air sacs are present in insects as tiny sacs that extend from their trachea, which is part of their respiratory system.

3. **Function of Air Sacs**:
- The primary function of air sacs is to increase respiratory efficiency. They help in maximizing the surface area available for gas exchange, which is essential for meeting the high metabolic demands of birds during flight.

4. **Conclusion**:
- Based on the information gathered, the question asks where air sacs are found. The correct answer is that air sacs are found in **all birds**.

5. **Final Answer**:
- Therefore, the correct option is **C. All birds have air sacs**.

---