You are answering a USMLE-style medical question. Question: A 72-year-old anthropologist with long-standing hypertension visits your office for a routine exam. You notice an abnormality on his laboratory results caused by his regimen of captopril and triamterene. What abnormality did you most likely find? Options: A) Hyperkalemia B) Hypernatremia C) Thrombocytopenia D) Anemia Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.