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': 'Diameter of varicose veins is \nSelect and explain. \nA. ≥ 1mm, B. ≥ 2mm, C. ≥ 4mm, D. ≥ 3mm', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Varicose veins are dilated tortuous\xa0subcutaneous veins\xa0≥ 3mm in diameter.', 'role': 'assistant'}]