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': 'Dextromethorphan differs from codeine in : \nSelect and explain. \nA. Its antitussive action can be blocked by naloxone, B. Depresses mucocilliary function of the airway mucosa, C. Addiction common, D. Causes no constipation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]