Acavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone, and caverns Secrets are hidden in caves. Given these facts, what are formed by carbonic acid in groundwater seeping through rock and dissolving limestone among the following options:
- aqueous solution
 - barrel-shaped
 - Calcium carbonate
 - Greenhouse gasses
 - hidden caves
 - a solute
 - swamp vegetation
 - a hydraulic system


 

     hidden caves    