Cardiovascular Drugs USMLE Step 1 Practice Question

A 62-year-old man with a 10-year history of hypertension presents to his primary care physician 4 weeks after starting a new antihypertensive medication. He reports improved urinary hesitancy and decreased nocturia. However, he now experiences orthostatic dizziness that occurs within minutes of standing from a seated or supine position. Today his blood pressure is 138/84 mmHg seated and 112/70 mmHg standing (heart rate 78 bpm in both positions). On digital rectal examination, his prostate is enlarged. The patient denies chest pain, palpitations, or syncope. Which of the following medications most likely explains both his improved lower urinary tract symptoms and his current adverse effect?