A 45-year-old female presents with fever (103°F), severe tachycardia (140 bpm), altered mental status, and a history of Graves' disease not adherent to medication. On examination, she has lid lag and tremor. What is the most crucial initial pharmacological step to inhibit new thyroid hormone synthesis?

✓ Correct Answer: Option C

In thyroid storm, the most crucial initial pharmacological step to inhibit new thyroid hormone synthesis is administering an antithyroid drug like propylthiouracil (PTU). PTU also inhibits peripheral conversion of T4 to T3. Iodine should be given *after* PTU to prevent worsening hyperthyroidism.