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: Dental
[{'content': 'According to Stanford-Binet test, non trainable type of\nmental retardation has an IQ of: \nSelect and explain. \nA. Below 20, B. Between 36-51, C. Above 51, D. Between 90 - 130', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]