This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histamine, 5-HT and PGs, Subject name: Pharmacology
Which of the following is most useful for reversing severe ergot induced vasospasm? 
Select and explain. 
A. Ergotamine, B. Methysergide, C. Nitroprusside, D. Phenoxybenzamine
C: Nitroprusside
Answer: C: Nitroprusside 
Explanation: Nitroprusside is a mixed dilator and is highly effective agent against ergot induced vasospasm. It is also the drug of choice for most of the hypeensive emergencies.