<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 72-year-old male presents to his primary care physician complaining of increased urinary frequency and a weakened urinary stream. He has a history of gout, obesity, diabetes mellitus, and hyperlipidemia. He currently takes allopurinol, metformin, glyburide, and rosuvastatin. His temperature is 98.6F 37C, blood pressure is 13085 mmHg, pulse is 90min, and respirations are 18min. Physical examination reveals an enlarged, non-tender prostate without nodules or masses. An ultrasound reveals a uniformly enlarged prostate that is 40mL in size. His physician starts him on a new medication. After taking the first dose, the patient experiences lightheadedness upon standing and has a syncopal event. Which of the following mechanisms of action is most consistent with the medication in question?? A: Dihydropyridine calcium channel blocker, B: Alpha-1-adrenergic receptor antagonist, C: Alpha-2-adrenergic receptor agonist, D: Non-selective alpha receptor antagonist, E: Selective muscarinic agonist,  <response>: Based on the information provided in the question stem, this patient has symptoms of benign prostatic hyperplasia BPH, including increased urinary frequency, weakened urinary stream, and an enlarged prostate on exam and ultrasound. His physician started him on a new medication to treat his BPH. After taking the first dose, he experienced orthostatic hypotension and syncope. This reaction is most consistent with an alpha-1 adrenergic receptor antagonist, which can cause vasodilation and hypotension. Alpha-1 receptors mediate smooth muscle contraction in the prostate and blood vessels. Blocking these receptors relaxes smooth muscle in the prostate to improve urinary flow, but also causes vasodilation and hypotension. The other options would not be expected to cause this reaction.B: Alpha-1-adrenergic receptor antagonist 