This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'Which one of the following is a rickettsial disease \nSelect and explain. \nA. Weils disease, B. Rocky mountain fever, C. Relapsing fever, D. Pontaic fever', 'role': 'user'}, {'content': "Answer: B \nExplanation: Rocky mountain spotted fever is caused by R.ricketsii.vector is dermacentar andersonii it is prevalent in noh america and South America. It is the most serious type of spotted fever Ref: AnanthNarayan and paniker's 10th edition", 'role': 'assistant'}]