This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'Citrate as a sole source of carbon is utilized by \nSelect and explain. \nA. Staphylococcus, B. Salmonella, C. Shigella, D. Escherichia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Citrate is used by salmonella as sole source of carbon But citrate test positive: Salmonella Typhimurium Salmonella Paratyphi A is citrate negative Ref: Elmer W Koneman 5th ed Pg 186', 'role': 'assistant'}]