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': 'Which of the following is a vinodilator? \nSelect and explain. \nA. Hydralazine, B. Minoxidil, C. Nitroprusside, D. Nifedipine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ref:Katzung 10/e p173-174;KDT 6/e p540 Hydralazine, minoxidil and nifedipine are primarily aerioler dilators where as nitroprusside is a mixed aerioler and venous dilator, therefore best answer here seems to be nitroprusside', 'role': 'assistant'}]