This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'Centrally acting sympatholytic agent used as antihypeensive agent is \nSelect and explain. \nA. Propanolol, B. Clonidine, C. Prazosin, D. Phenoxybenzamine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Refer kDT 6/e p540 Clonidine, sold as the brand name Catapresamong others, is a medication used to treat high blood pressure, attention deficit hyperactivity disorder, drug withdrawal(alcohol, opioids, or smoking), menopausal flushing, diarrhea, and ceain pain conditions. It is used by mouth, by injection, or as a skin patch. Onset of action is typically within an hour with the effects on blood pressure lasting for up to eight hours', 'role': 'assistant'}]