This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Venous Disorders, Subject name: Surgery
[{'content': 'Varicose veins of size less than __can be best treated by sclerotherapy: \nSelect and explain. \nA. 2 mm, B. 3 mm, C. 4 mm, D. 6 mm', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sclerotherapy is useful for dealing with minor varicosities (<3 mm) and recurrences in the calf and lower leg. Amount of sclerosants used in treatment of varicose veins is 0.5 ml.', 'role': 'assistant'}]