<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 45-year-old-man presents to the physician with complaints of intermittent episodes of severe headaches and palpitations. During these episodes, he notices that he sweats profusely and becomes pale in complexion. He describes the episodes as coming and going within the past 2 months. His temperature is 99.3F 37.4C, blood pressure is 165118 mmHg, pulse is 126min, respirations are 18min, and oxygen saturation is 90 on room air. Which of the following would be the first medication given to treat this patients most likely diagnosis?? A: Phenoxybenzamine, B: Phentolamine, C: Pilocarpine, D: Prazosin, E: Propanolol,  <response>: This is a clinical vignette describing a 45-year-old man with intermittent episodes of severe headaches, palpitations, profuse sweating, and pallor. The vitals given indicate hypertension, tachycardia, and hypoxemia. The symptoms and vitals are consistent with a diagnosis of pheochromocytoma, which is characterized by episodic release of catecholamines like norepinephrine from a tumor of the adrenal medulla. The question asks for the first medication to treat this condition. Phenoxybenzamine, an alpha blocker, is the correct choice as it blocks the alpha-adrenergic effects of catecholamines released by the tumor. Phentolamine is also an alpha blocker but is shorter acting. Pilocarpine is a cholinergic agonist used for dry eyesmouth. Prazosin is an alpha blocker but is not first-line. Propranolol, a beta blocker, would be contraindicated as an initial treatment since blocking beta receptors alone can lead to unopposed alpha stimulation and hypertensive crisis.A: Phenoxybenzamine 