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: Skin
[{'content': 'H. ducreyi causes: \nSelect and explain. \nA. Soft chancre, B. Hard chancre, C. Pustule, D. Painless chancre', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Soft chancre', 'role': 'assistant'}]