Vertebrates having air sacs connected to lungs for supplement respiration are

Options

A. Birds
B. Reptiles
C. Mammals
D. Amphibia

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about vertebrates that have air sacs connected to their lungs for supplemental respiration. We need to identify which group of vertebrates possesses this feature.

2. **Analyzing the Options**: The options provided are:
- A) Birds
- B) Reptiles
- C) Mammals
- D) Amphibians

3. **Identifying Key Features**:
- Air sacs are additional structures that assist in respiration.
- These structures are specifically known to be present in birds.

4. **Recalling Respiratory Systems**:
- Birds have a unique respiratory system that includes air sacs. This system allows for a continuous flow of air through the lungs, which is essential for their high metabolic demands, especially during flight.

5. **Confirming the Correct Answer**:
- Among the options, birds (A) are the only vertebrates that have air sacs connected to their lungs for supplemental respiration. This feature is not found in reptiles, mammals, or amphibians.

6. **Conclusion**: Therefore, the correct answer to the question is **Birds**.