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': 'Mechanism of action of clonidine is mediated by which of the following receptors? \nSelect and explain. \nA. Alpha 1, B. Alpha 2, C. Beta 1, D. Beta 2', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]