This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'For obesity BMI should be - \nSelect and explain. \nA. >=20, B. >=50, C. >=40, D. >=30', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref-Park&;s textbook of preventive and social medicine 24th edition. .', 'role': 'assistant'}]