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: Social & Preventive Medicine
[{'content': 'Incubatory carrier seen in -a)  Cholerab)  Bubonic plaguec)  Mumpsd)  Measles e)  Influenza \nSelect and explain. \nA. ba, B. aec, C. cde, D. ce', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]