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: Unknown
Size of particle for aerosol therapy is? 
Select and explain. 
A. 0.5-1 µ, B. 1-5 µ, C. 5-10 µ, D. 10-15 µ
B: 1-5 µ
Answer: B: 1-5 µ 
Explanation: Reference: KDT, Essentials of Medical Pharmacology, 7th ed., Pg. 232.
Efficacy of aerosolized drug depends on the particlesize: 1–5 μm diameter particles deposit on the bronchioles and effectively deliver the drug. Larger particles settle on the oropharynx, while very fine particles do not settle anywhere and are exhaled out. On an average only ~10% of the inhaled drug reaches the site of action.