Blood Levels of Which of the Following Substances Is Decreased $\left(\mathrm{T}_{3}\right)$

Blood levels of which of the following substances is decreased in Graves disease?

A) Triiodothyronine $\left(\mathrm{T}_{3}\right)$
B) Thyroxine $\left(\mathrm{T}_{4}\right)$
C) Diiodotyrosine (DIT)
D) Thyroid-stimulating hormone (TSH)
E) Iodide ( $\left.\mathrm{I}^{-}\right)$