Which of the Following Is True About the Action of Iodide

Which of the following is true about the action of iodide solutions for hyperthyroid states?

A) High doses of iodide cause an immediate reduction in the release of thyroid hormone.
B) Iodide reduces the blood supply to the thyroid gland and makes it firmer.
C) Iodide has a long half-life and greatly reduces the release of thyroid hormone for up to one month.
D) Both A and B.