This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Micronutrient Mineral Deficiencies, Subject name: Pediatrics
[{'content': 'Keshan disease is due to deficiency of? \nSelect and explain. \nA. Selenium, B. Chromium, C. Zinc, D. Iodine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans (a) Selenium', 'role': 'assistant'}]