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': 'The following is the etiological agent of Rocky mountain spotted fever - \nSelect and explain. \nA. Rickettsia rickettsii, B. Rochalimaea quintana, C. Rickettsia tsutsugamushi, D. Coxiella burnetii', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]