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: Medicine
[{'content': 'Keshan disease is caused due to deficiency of: \nSelect and explain. \nA. Selenium, B. Chromium, C. Iodine, D. Iron', 'role': 'user'}, {'content': "Answer: A \nExplanation: Keshan disease is an endemic cardiomyopathy found in children and young women residing in regions of China where dietary intake of selenium is low ( Ref: Harrison's principle of internal medicine 17th edition, chapter 71.", 'role': 'assistant'}]