This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Pediatrics
[{'content': 'Mental retardation is seen in? \nSelect and explain. \nA. Phenylketonuria, B. Alkaptonuria, C. Albinism, D. Von Gierke disease', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mental retardation is feature of PKU due to elevated level of phenylalanine hydroxylase in brain.', 'role': 'assistant'}]