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': 'All are true about Rickettsia except - \nSelect and explain. \nA. obligate intracellular, B. Gram +ve bacillus, C. Arthropods are vector, D. Weil felix test is diagnostic', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]