A nurse is talking with a client whose thyroid-stimulating hormone (TSH) level will be measured. Which of the following statements by the nurse explains the purpose of this test?

"This test detects antithyroid antibodies in your blood."

"This test determines whether your thyroid gland is overactive, appropriately active, or underactive."

"This test measures the absorption of iodine and how it relates to the thyroid gland."

"This test measures the amount of thyroid hormone that attaches to a protein in your blood."