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: Microbiology
[{'content': "The time gap between appearance of koplik's spot and cutaneous rash in measles is: \nSelect and explain. \nA. 24 Hrs, B. 3-4 days, C. 2 weeks, D. 10 days", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]