This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Cryosurgery utilizes which of the following? 
Select and explain. 
A. Nitrous oxide, B. Carbon dioxide, C. Liquid oxygen, D. Nitric dioxide
A: Nitrous oxide
Answer: A: Nitrous oxide 
Explanation: None