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': "Rett'\\s syndrome occurs due to deficiency of – \nSelect and explain. \nA. Niacin, B. Biotin, C. Carotene, D. Vitamin D", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]