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': 'Aeriolar dilators used in the treatment of CHF \nSelect and explain. \nA. Hydralazine, B. Nifedipine, C. Prazosin, D. Enalaprin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Nifedipine is a calcium channel blocker. Enalapril is an ACE inhibitor. Prazosin is alpha 1 blocker. Hydralazine is an aerial dilator and potassium channel opener (REF.Essentials of medical pharmacology KD TRIPATHI 8 Edition)', 'role': 'assistant'}]