impact of humans on Earth. effect of gravity on animals. history of animal species on Earth. likelihood that dinosaurs will reappear.
I gave my students this multiple choice question: In 1971, the bones of an extinct flying dinosaur were discovered. This kind of discovery helps everyone learn more about

Only one answer is correct among these 4 choices:
- impact of humans on Earth.
- effect of gravity on animals.
- history of animal species on Earth.
- likelihood that dinosaurs will reappear.

Could you tell me which one is correct?

history of animal species on Earth.