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': 'True statement about listeria: \nSelect and explain. \nA. Gram negative bacillus, B. Motile by peritrichous flagella, C. Commonest cause of community acquired meningitis, D. Only one serovar is known', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is. 'b' i. e., Motile by peritrichous flagella", 'role': 'assistant'}]