You are answering a USMLE-style medical question. Question: A 62-year-old man presents to his primary care doctor with continued hypertension despite adherence to multiple anti-hypertensive medications. The physician suspects that the patient may have elevated aldosterone levels and wants to initiate a trial of an aldosterone receptor antagonist. The patient is very concerned about side effects, particularly impotence and gynecomastia, as he had a friend who took a similar medication and had these side-effects. Which of the following is the best medication to initiate, given his concerns and the physician's diagnosis? Options: A) Spironolactone B) Eplerenone C) Triamterene D) Ethacrynic acid Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.