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': "Buerger's disease affects all except \nSelect and explain. \nA. Lymphatic’s, B. Small vessels, C. Nerves, D. Veins", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]