This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
[{'content': 'Idazoxan is a (REPEAT) \nSelect and explain. \nA. Alpha 1 agonist, B. Alpha 1 blocker, C. Alpha 2 blocker, D. Alpha 2 agonist', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Yohimbine, idazoxan -selective alpha 2 blockers.', 'role': 'assistant'}]