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: Social & Preventive Medicine
[{'content': 'Rickettsial agent of Epidemic typhus isRickettsial agent of Epidemic typhus is \nSelect and explain. \nA. R. canorii, B. R. typhi, C. R. tsutsugamushi, D. R. prowazekii', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]