The species are both herbivores. The species have similar bone structure. The species live in the same environment. The species both obtain oxygen from the air.
I gave my students this multiple choice question: Which of the following observations best supports the conclusion that two animal species evolved from a common ancestor in recent geological history?

Only one answer is correct among these 4 choices:
- The species are both herbivores.
- The species have similar bone structure.
- The species live in the same environment.
- The species both obtain oxygen from the air.

Could you tell me which one is correct?

The species have similar bone structure.