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
Alpha I blocker without any effect on blood pressure is: 
Select and explain. 
A. Tamsulosin, B. Prazosin, C. Doxazosin, D. Terazosin
A: Tamsulosin
Answer: A: Tamsulosin 
Explanation: None