MSFinals-6682

A 67-year-old male visits his doctor with complaints of urological symptoms. He reports frequent nighttime urination, urgency, difficulty initiating urination, and a weak stream. During a digital rectal exam, the doctor notes a smooth but enlarged prostate and orders a blood test to check PSA levels. To alleviate his symptoms, the doctor prescribes tamsulosin.

What is the mechanism of action of tamsulosin?