A nearby volcano is tall. A nearby volcano is inactive. A nearby volcano is about to erupt. A nearby volcano had once been active.
I gave my students this multiple choice question: Students studying rocks notice that in a particular location there are many igneous rocks that are very similar. This observation best supports which statement?

Only one answer is correct among these 4 choices:
- A nearby volcano is tall.
- A nearby volcano is inactive.
- A nearby volcano is about to erupt.
- A nearby volcano had once been active.

Could you tell me which one is correct?

A nearby volcano had once been active.