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': 'Mycobacterium causeing skin ulcer: \nSelect and explain. \nA. M.smegmatis, B. M.scrofulaceum, C. M.ulcerans, D. M.fouitum', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. M. ulcerans', 'role': 'assistant'}]