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. Vit D", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Biotin", 'role': 'assistant'}]