A client is being treated for hyperthyroidism with propylthiouracil (PTU). The nurse knows that the action of this drug is to
A. decrease the amount of the thyroid-stimulating hormone circulating in the blood
B. increase the amount of thyroid-stimulating hormone circulating in the blood
C. increase the amount of T4 and decrease the amount of T3 produced by the thyroid
D. inhibit synthesis of T3 and T4 by the thyroid gland