Task: Question Answering
Input (English): Process:  -Limestone is located under the soil -Rain picks up carbon dioxide as it falls to earth -The rain falls on the soil over the limestone -The carbon dioxide in the rain washes through the soil -The carbon dioxide turns into acid -The acid in the rain gets to the limestone below the soil -The acid dissolves the limestone -Acid continues to erode the limestone with more rain over time -The eroded limestone sometimes forms caves.
 Question: What is the effect of there is oxygen that could be cleared on more/larger caverns.?
Output (English): none