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
[{'content': 'H1 blockers are useful as:- \nSelect and explain. \nA. Antacids, B. Anti-allergic, C. Anti-asthmatics, D. Anti-migraine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]