This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: A.N.S., Subject name: Pharmacology
Which of the following is selective alpha antagonist? 
Select and explain. 
A. Propanolol, B. Prazosin, C. Phentolamine, D. Clonidine
B: Prazosin
Answer: B: Prazosin 
Explanation: Ans. B. PrazosinPrazosin is selective alpha 1 blocker which used in patients suffering from BHP. They also used in hypertension. Phentolamine is nonselective alpha blocker. Clonidine is alpha 2 agonists.