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': 'Post dural puncture headache, true about ? \nSelect and explain. \nA. Common in elderly, B. Small bore needle prevents it, C. Early ambulation increases incidence, D. All', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. (Small bore needle prevents it)', 'role': 'assistant'}]