This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Which of the following does not have non - human reservoir 
Select and explain. 
A. Salmonella typhi, B. N. Gonorrhoea, C. E coli, D. Clostridium tetani
A: Salmonella typhi
Answer: A: Salmonella typhi 
Explanation: Reservoir of infection: man is only the known reservoir of infection, viz cases and carries Cases- mild , moderate and severe Carriers -temporary or chronic Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 257