The parents are of a different genus and a different species. The parents are of a different species, but of the same genus. The parents are of the same genus and of the same species. The parents are of the same species, but of a different genus.
I gave my students this multiple choice question: Two organisms mate and produce offspring. Which of the following statements best explains why the offspring are unable to reproduce?

Only one answer is correct among these 4 choices:
- The parents are of a different genus and a different species.
- The parents are of a different species, but of the same genus.
- The parents are of the same genus and of the same species.
- The parents are of the same species, but of a different genus.

Could you tell me which one is correct?

The parents are of a different species, but of the same genus.