Fact 1: Acavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone.

Fact 2: Caverns are characterized by enormous rooms.

Given the two facts above, answer the question "what are formed by carbonic acid in groundwater seeping through rock dissolving limestone" with the following options: 
- oceans
 - Calcium carbonate
 - coral reefs
 - enormous rooms
 - a solute
 - creeks
 - Greenhouse gasses
 - a hydraulic system


 

    enormous rooms     