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: Anaesthesia
Which anaesthetic gas is contraindicated in the presence of pneumothorax ? 
Select and explain. 
A. Halothane, B. Isoflurane, C. Nitrous oxide, D. Chloroform
C: Nitrous oxide
Answer: C: Nitrous oxide 
Explanation: None