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
[{'content': 'Which of the following does not have non - human reservoir \nSelect and explain. \nA. Salmonella typhi, B. N. Gonorrhoea, C. E coli, D. Clostridium tetani', 'role': 'user'}, {'content': "Answer: A \nExplanation: 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", 'role': 'assistant'}]