1. The problem asks to find the translation vector that maps triangle ITR (preimage) onto triangle I'T'R' (image). 2. A translation vector $\vec{v} = \langle x, y \rangle$ moves every point of the preimage by adding $x$ to the x-coordinate and $y$ to the y-coordinate. 3. To find the translation vector, pick a corresponding point from the preimage and image, for example, point I and point I'. 4. Suppose $I = (x_1, y_1)$ and $I' = (x_2, y_2)$. Then the translation vector is: $$\vec{v} = \langle x_2 - x_1, y_2 - y_1 \rangle$$ 5. From the graph description, the translation moves the triangle right and down. 6. This means $x_2 - x_1 > 0$ and $y_2 - y_1 < 0$. 7. Among the options, only option D $\langle 6, -4 \rangle$ matches this direction. 8. Therefore, the translation vector is: $$\boxed{\langle 6, -4 \rangle}$$