This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Legionella, Subject name: Microbiology
[{'content': 'Pontiac fever is caused by? \nSelect and explain. \nA. Legionella, B. Mycoplasma, C. Rickettsia, D. Salmonella', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. (a) LegionellaRef: BRS microbiology 4/e, p 50, Harrison's 17/e, chapter 141", 'role': 'assistant'}]