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': 'True about Pertussis is/are -a) Incubation period is 7-14 daysb) Main source of infection is chronic carriersc) Can affect any aged) Secondary attack rate in unimmunised persons is 90%e) More common in summers \nSelect and explain. \nA. abc, B. acd, C. bc, D. bde', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]