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': 'Venous ulcer has following characteristics except \nSelect and explain. \nA. Irregular wound margins, B. Deep pale wound bed, C. Usually no pain, D. Ruddy, granular tissue', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Venous ulcer is superficial wound.', 'role': 'assistant'}]