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': 'Healthy carries are present in all except- \nSelect and explain. \nA. Typhoid, B. Chorera, C. Diphtheria, D. Peussis', 'role': 'user'}, {'content': "Answer: A \nExplanation: Healthy carriers emerge from subclinical cases. They are victims of subclinical cases who have developed carrier state without suffering from ove diseases but are neveheless shedding the disease agent. Eg polio, cholera, meningococcal meningitis, salmonellosis, and diphtheria. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 104", 'role': 'assistant'}]