A 27-year-old woman at 9 weeks of gestation presents to her obstetrician complaining of a 6-week history of heat intolerance, fine resting tremor, unintentional weight loss of 8 pounds, and palpitations. Her temperature is 37.8°C, blood pressure is 138/82 mmHg, heart rate is 112 beats/min, and respiratory rate is 18 breaths/min. Physical examination reveals warm, moist skin, a diffusely enlarged nontender thyroid gland, and a fine tremor of the outstretched hands. Ophthalmologic examination shows mild lid lag bilaterally. Laboratory testing demonstrates a suppressed TSH of 0.01 mIU/L and an elevated free T4 of 3.8 ng/dL. Concerned about the risks of methimazole embryopathy during the first trimester, her physician instead initiates a medication that inhibits thyroid peroxidase and additionally blocks peripheral conversion of T4 to the more active T3. Which of the following drugs was most likely prescribed?

1. A)Radioactive iodine
2. B)Levothyroxine
3. C)Propranolol
4. D)PropylthiouracilGABARITO
5. E)Methimazole