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
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: 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.