They all lay eggs. They all have feathers. They all have a backbone. They are all warm-blooded.
I gave my students this multiple choice question: Lamar learned that birds, mammals, and reptiles are all vertebrates. Which characteristic do all vertebrates share?

Only one answer is correct among these 4 choices:
- They all lay eggs.
- They all have feathers.
- They all have a backbone.
- They are all warm-blooded.

Could you tell me which one is correct?

They all have a backbone.