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 Widal test in typhoid is? \nSelect and explain. \nA. 0-antigen titre remains positive for several months & reaction to it is rapid, B. H-antigen titre remains positive for several months & reaction to it is rapid, C. Both remain positive for several months & reaction to both is rapid, D. None', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., H-antigen titre remains positive for several months and reaction to it is rapid", 'role': 'assistant'}]