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: Pediatrics
[{'content': "Not a feature of Hartnup's disease \nSelect and explain. \nA. Cerebellar ataxia, B. Cutaneous photosensitivity, C. Mental retardation, D. Psychological disturbance", 'role': 'user'}, {'content': "Answer: C \nExplanation: In hartnup's disease, mental development is normal.", 'role': 'assistant'}]