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: Medicine
[{'content': 'A mill-wheel type of murmur during laparoscopy suggests - \nSelect and explain. \nA. Tension pneumothorax, B. Intraabdominal bleeding, C. Gas embolism, D. Pre-existing valvular disease', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]