You are presented with the quiz "what are formed by carbonic acid in groundwater seeping through rock dissolving limestone" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "acavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone" and "caverns are characterized by enormous rooms". 

So, what's the best answer to the question?


 

    enormous rooms       