This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Measles is said to be infectious \nSelect and explain. \nA. 4 days before appearance of rash, B. After 4 days of rash, C. 4 days before and 5 days after rash appearance, D. Only during the incubation period', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Measles transmission Measles case is infective 4 days before to 5 days after appearance of rash More commonly seen in winters and early spring in India Incubation period : 10-14 days Only one type of vaccine (Live attenuated) Ref: Park 25th edition Pgno : 159-162', 'role': 'assistant'}]