You are answering a USMLE-style medical question. Question: A 29-year-old woman presents to the clinic after several months of weight loss. She noticed a 6.8 kg (15 lb) unintentional weight loss over the preceding several months. She has not changed her diet or exercise habits. She also reports feuding with her boyfriend over the temperature of their shared apartment, as she always feels warmer than he does. The vital signs include: heart rate 110/min and blood pressure 146/78 mm Hg. The physical exam is notable for warm and slightly moist skin. She also exhibits a fine tremor in her hands when her arms are outstretched. The urine pregnancy test is negative. Which of the following is the best single treatment option for this patient? Options: A) Glucocorticoids B) Methimazole C) Propranolol D) Radioiodine therapy Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.