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: Pathology
[{'content': 'All are true about the Widal test, except : \nSelect and explain. \nA. Baseline differs depending on the endemicity of disease., B. O antibodies last longer and hence are not an indicator of recent infection, C. H antigen cannot differentiate between subtypes, D. High titre value in a single Widal test, not confirmation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]