A nurse is caring for a client who has a low thyroid stimulating hormone (TSH) level and elevated thyroxine (T4) and triiodothyronine (13) levels. Which of the following medications should the nurse anticipate to treat Graves' disease?

A. Propylthiouracil (PTU): PTU is an antithyroid medication used to treat Graves' disease by inhibiting thyroid hormone production. B. Morphine sulfate (Astramorph): Morphine is a pain medication and is not used for Graves' disease. C. Sucralfate (Carafate): Sucralfate is used to treat ulcers, not thyroid disorders. D. Metformin (Glucophage): Metformin is used for diabetes, not for thyroid disorders.