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: Social & Preventive Medicine
[{'content': 'Wind velocity is normally recorded at a height of – \nSelect and explain. \nA. 1 metre, B. l0 metres, C. 15 metres, D. 20 metres', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]