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': 'Which among the following NOT a pharmacological action of opioids \nSelect and explain. \nA. Cough suppression, B. Anti-emesis, C. Miosis, D. Truncal rigidity', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]