This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition, Subject name: Medicine
[{'content': 'Keshan disease is due to deficiency of - \nSelect and explain. \nA. Selenium, B. Chromium, C. Copper, D. Manganese', 'role': 'user'}, {'content': "Answer: A \nExplanation: selenium def cause cardiomyopathy in children known as Keshan's disease which is endemic cardiomyopathy Ref Harrison 20th edition pg 99e", 'role': 'assistant'}]