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': 'A Person is underweight if BMI is \nSelect and explain. \nA. <25, B. <18.5, C. <22, D. <20', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]