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
[{'content': 'If pneumocephalus created either by surgery or by performance of a pneumoencephalogram, it is suggested that nitrous oxide be avoided for how many days – \nSelect and explain. \nA. 4 days, B. 5 days, C. 6 days, D. 7 days', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Once the pneumoencephalum has developed nitrous oxide should not be used for 1 week.', 'role': 'assistant'}]