This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Measles, Subject name: Social & Preventive Medicine
[{'content': 'Measles is infective for how many days before the onset of rash - \nSelect and explain. \nA. 10 days, B. 4 days, C. 1 days, D. on same', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., 4 days Period of communicability in important respiratory infections# Chicken pox: 1 - 2 days before to 4 - 5 days after appearance of rash.# Measles: 4 days before to 5 days after appearance of rash.# Rubella: 7 days before symptoms to 7 days after appearance of rash.# Mumps: 4-6 days before symptoms to 7 days thereafter.# Influenza: 1 - 2 days before to 1 - 2 days after onset of symptoms.# Diphtheria: 14-28 days from disease onset.# Pertussis: 7 days after exposure to 3 weeks after paroxysmal stage.", 'role': 'assistant'}]