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 blockers are useful as:- 
Select and explain. 
A. Antacids, B. Anti-allergic, C. Anti-asthmatics, D. Anti-migraine
B: Anti-allergic
Answer: B: Anti-allergic 
Explanation: None