A 28-year-old woman, 10 weeks pregnant, is diagnosed with new-onset Graves' disease. She has symptoms of hyperthyroidism, including tachycardia, heat intolerance, and weight loss despite increased appetite. Thyroid function tests show suppressed TSH and elevated free T4. Which of the following is the most appropriate initial treatment?
✓ Correct Answer: Option C
Propylthiouracil (PTU) is the preferred antithyroid medication during the first trimester of pregnancy due to methimazole's known teratogenic effects. After the first trimester, methimazole may be preferred.