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': "Vi antigen found in - \nSelect and explain. \nA. Salmonella paratyphi 'C', B. Salmonella Typhi, C. Salmonella dublin, D. All", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans :D.)All The Vi antigen, is a capsular polysaccharide found mainly in Salmonella typhi and S. paratyphi C, as well as in a few strains of S. dublin and Citrobacter freundii', 'role': 'assistant'}]