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
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 
Select and explain. 
A. abc, B. acd, C. bc, D. bde
B: acd
Answer: B: acd 
Explanation: None