Which of the Following Explains Why Alpha Blockers Would Be

Which of the following explains why alpha blockers would be useful for drug therapy of BPH?

A) Alpha blockers antagonize alpha receptors,causing smooth muscle of the prostate and bladder to relax,improving urine flow.
B) Administration of alpha blockers causes prostate muscle to constrict,allowing for easier control of the flow of urine.
C) Alpha blockers act as agonists on alpha receptors,causing smooth muscle relaxation,which improves urethral resistance.
D) Alpha blockers block the normal alpha response,constricting urethral resistance,which allows better control over the flow of urine.