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': 'True statement of Buerger’s disease is/are \nSelect and explain. \nA. Small and medium sized vessels involved, B. Commonly involves upper limb than lower limbs, C. Common in male, D. Common in female', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]