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': 'Which one of the following micro-organism uses antigenic variation as a major means of variation as an evading host defences? \nSelect and explain. \nA. Streptococcus pneumoniae, B. Borrelia recurrentis, C. Mycobacterium tuberculosis, D. Listeria monocytogenes', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]