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': 'Salmonella typhi is the causative agent of typhoid fever. The infective dose of S.typhi - \nSelect and explain. \nA. One bacillus, B. 108 - 1010 bacilli, C. 102 - 105 bacilli, D. 1 - 10 bacilli', 'role': 'user'}, {'content': 'Answer: C \nExplanation: All Salmonella infections begin with ingestion of organisms, most commonly in contaminated food or water. The infectious dose is\xa0103–106 colony-forming units.', 'role': 'assistant'}]