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': 'All of the following are vasodilators except \nSelect and explain. \nA. Methyl dopa, B. Nitroprusside, C. Hydralazine, D. Diazoxide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Methyldopa is a centrally acting alpha-agonist Hydralazine, diazoxide, and nitroprusside are vasodilators. Hydralazine, diazoxide- aeriolar dilators- potassium channel openers Nitroprusside- both aeriolar and venous dilator REF.Essentials of Medical Pharmacology-kD Tripathi 8th ed.', 'role': 'assistant'}]