You are presented with the question "What is one element used to create caves?" and the following answer choices: 
- sunlight
 - heat energy
 - Calcium carbonate
 - hydrogen and oxygen
 - calcite
 - carbonic acid
 - less water
 - salinity

Now knowing that acavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone and when caves contain connecting rooms, they are called caverns, choose the best answer.


 

      carbonic acid   