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: Pharmacology
[{'content': 'NMDA blocker used as antitussive is \nSelect and explain. \nA. Pholcodeine, B. Dextromethorphan, C. Diphenhydramine, D. Aprepitant', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Dextromethorphan is a NMDA blocker which is a less potent antitussive. Side effects include addiction liability & hallucination.', 'role': 'assistant'}]