Birds lay eggs and reptiles do not. Reptiles are meat-eaters and birds are not. Birds breathe oxygen and reptiles do not. Reptiles are cold-blooded and birds are not.
I gave my students this multiple choice question: What is one difference between birds and reptiles?

Only one answer is correct among these 4 choices:
- Birds lay eggs and reptiles do not.
- Reptiles are meat-eaters and birds are not.
- Birds breathe oxygen and reptiles do not.
- Reptiles are cold-blooded and birds are not.

Could you tell me which one is correct?

Reptiles are cold-blooded and birds are not.