This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mental Health, Subject name: Social & Preventive Medicine
[{'content': 'Mental retardation is defined if IQ is below:- \nSelect and explain. \nA. 60, B. 70, C. 80, D. 90', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Normal IQ 70 or above. Mild mental retardation = 50-70 Moderate mental retardation = 35-49 Severe mental retardation = 20-34 Profound mental retardation = <20.', 'role': 'assistant'}]