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': 'Not true about measles \nSelect and explain. \nA. Carriers are the source of infection, B. Koplik spots are pathognomonic, C. Edmonston zagreb strain used for vaccine, D. Incubation period is 2 weeks', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]