This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Child Psychiatry, Subject name: Psychiatry
[{'content': 'A patient with IQ 30 will be diagnosed with: \nSelect and explain. \nA. Mild mental retardation, B. Moderate mental retardation, C. Severe mental retardation, D. Profound mental retardation', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Normal 90-109 Borderline 70-89 Mild MR 50-69 Moderate MR 35-49 Severe MR 20-34 Profound MR <20', 'role': 'assistant'}]