This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histamine, 5-HT and PGs, Subject name: Pharmacology
H1 antihistaminic having best topical activity is: 
Select and explain. 
A. Loratidine, B. Cetrizine, C. Astemizole, D. Azelastine
D: Azelastine
Answer: D: Azelastine 
Explanation: Azelastine and olopatadine have maximum topical action and are therefore used for local conditions like allergic rhinitis and allergic conjunctivitis.