Acavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone, and when caves contain connecting rooms, they are called caverns. Given these facts, what is one element used to create caves among the following options:
- sunlight
 - heat energy
 - Calcium carbonate
 - hydrogen and oxygen
 - calcite
 - carbonic acid
 - less water
 - salinity


 

      carbonic acid   