Birds differ from reptiles in

Options

A. Being endothermic
B. Being ectothermic
C. both
D. Being viviparous

Answer

To determine how birds differ from reptiles, we can analyze the characteristics of both groups based on the options provided.

### Step-by-Step Solution:

1. **Understanding Endothermic vs. Ectothermic:**
- Birds are classified as **endothermic**, which means they are **warm-blooded**. This allows them to regulate their body temperature internally, regardless of the external environment.
- Reptiles, on the other hand, are classified as **ectothermic**, meaning they are **cold-blooded**. They rely on external sources of heat, such as sunlight, to regulate their body temperature.

2. **Evaluating the Options:**
- **Option 1: Being Endothermic** - This is true for birds. They can maintain a stable internal body temperature.
- **Option 2: Being Ectothermic** - This is false for birds, as they are not cold-blooded.
- **Option 3: Both Options are Correct** - This is incorrect since only the first option is true.
- **Option 4: Being Viviparous** - This is also incorrect for birds, as they lay eggs (oviparous) rather than giving live birth.

3. **Conclusion:**
- The primary difference between birds and reptiles, based on the options provided, is that birds are **endothermic** while reptiles are **ectothermic**. Therefore, the correct answer is **Option 1: Being Endothermic**.

### Final Answer:
**Birds differ from reptiles in being endothermic.**

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