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: Medicine
True about asthma -a) Increasing incidence day by dayb) Allergic asthma common in older patientsc) Increase in IgE in idiosyncratic asthmad) Bronchoconstriction 
Select and explain. 
A. b, B. c, C. ad, D. ab
C: ad
Answer: C: ad 
Explanation: None