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: Surgery
[{'content': "Drug used for Burger's disease- \nSelect and explain. \nA. Xanthinol micotinate, B. Propranolol, C. GTN, D. All the above", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]