Answer the following question given this paragraph: 

Scientists don’t know for certain why magnetic reversals occur, but there is hard evidence that they have for hundreds of millions of years. The evidence comes from rocks on the ocean floor. Look at Figure below . They show the same ridge on the ocean floor during different periods of time.


Q: Where does evidence that magnetic reversals occur come from?

 Choices:

- snow

- Volcanoes

- air

- rocks on ocean floor

A:
rocks on ocean floor
