You are presented with the question "What chemical creates a cavern?" and the following answer choices: 
- carbonic acid
 - heating liquids
 - hydrogen and oxygen
 - aqueous solution
 - salt
 - oxygen
 - hydrogen
 - flow of electrons

Now knowing that acavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone and carbon dioxide dissolved in rainwater forms carbonic acid, choose the best answer.


 

 carbonic acid        