This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy & Physiology (Peritonium), Subject name: Surgery
[{'content': 'Most common gas used for pneumoperitoneum \nSelect and explain. \nA. Nitrogen, B. CO2, C. O2, D. Air', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) CO2 (Ref: Campbell Urology 11th 211)* CO2 is the most commonly used gas for laparoscopy because it is colourless, non combustible, very soluble in blood and inexpensive.', 'role': 'assistant'}]