It was once below a waterfall. It was once part of a riverbed. It was once covered by an ocean. It was once near a freshwater lake.
I gave my students this multiple choice question: A researcher found shark fossils on top of a mountain. This evidence suggests which of the following about this region?

Only one answer is correct among these 4 choices:
- It was once below a waterfall.
- It was once part of a riverbed.
- It was once covered by an ocean.
- It was once near a freshwater lake.

Could you tell me which one is correct?

It was once covered by an ocean.