This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mycobacteria, Subject name: Microbiology
[{'content': 'Buruli ulcer is caused by: \nSelect and explain. \nA. M. tuberculosis, B. M. ulcerans, C. M. marinum, D. M. fortuitum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: b (M. ulcerans) Ref: Ananthanarayan, 7th ed, p. 367M.ulcerans is the only toxin producing mycobacterium, causing buruli ulcer', 'role': 'assistant'}]