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
All of the following are vasodilators except: 
Select and explain. 
A. Methyl dopa, B. Nitroprusside, C. Hydralazine, D. Diazoxide
A: Methyl dopa
Answer: A: Methyl dopa 
Explanation: None