You are presented with the question "what are caverns formed from?" and the following answer choices: 
- storing water
 - streams
 - fossil fuels
 - limestone
 - streams.
 - Rocks
 - crust
 - mines

Now knowing that acavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone and limestone caves are formed when acids attack and dissolve the calcite in limestone, choose the best answer.


 

    limestone     