This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti Adrenergic System, Subject name: Pharmacology
Alpha 1 blocker without any effect on blood pressure is? 
Select and explain. 
A. Tamsulosin, B. Prazosin, C. Oxazocin, D. Terazocin
A: Tamsulosin
Answer: A: Tamsulosin 
Explanation: ANSWER: (A) TamsulosinREF: KDT 7th ed p. 135, Goodman Gillmans 11th ed p. 173Tamsulosin, a benzenesulfonamide, is an al receptor antagonist with some selectivity fora1A and a1D subtypes, favoring a1A blockade in prostate. Tamsulosin is efficacious in the treatment of BPH with little effect on blood pressure,