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: Psychiatry
[{'content': 'A male child of 15 years, with a mental age of 9 years has an IQ of: \nSelect and explain. \nA. 50, B. 60, C. 70, D. 80', 'role': 'user'}, {'content': "Answer: B \nExplanation: Intelligence quotient (IQ), is obtained by dividing the subject's mental age (as determined by the Binet-Simon scale) by his chronological age (up to the 14th year) and multiplying the result by 100. IQ of this child is = 9/15 * 100= 60 Ref: Introduction to Psychology By J. Mahmud, Page 236.", 'role': 'assistant'}]