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
Salmonella typhi is the causative agent of typhoid fever. The infective dose of S.typhi - 
Select and explain. 
A. One bacillus, B. 108 - 1010 bacilli, C. 102 - 105 bacilli, D. 1 - 10 bacilli
C: 102 - 105 bacilli
Answer: C: 102 - 105 bacilli 
Explanation: All Salmonella infections begin with ingestion of organisms, most commonly in contaminated food or water. The infectious dose is 103–106 colony-forming units.