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': 'Prolonged salmonella septicemia is caused by - \nSelect and explain. \nA. S. enteritidis, B. S. cholerae-suis, C. S. typhimurium, D. S. typhi', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]