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: Microbiology
[{'content': 'Who discovered Treponema pallidum \nSelect and explain. \nA. Schaudinn and Hoffmann, B. Paul Ehrilich, C. Roux and Yersin, D. Yersin and Kitasato', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Schaudinn and Hoffmann discovered Treponema pallidum.', 'role': 'assistant'}]