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: Social & Preventive Medicine
[{'content': 'Keshan cardiomegaly occur due to deficiency of \nSelect and explain. \nA. Zinc, B. Copper, C. Selenium, D. Iron', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]