NDA 2020 Mathematics question

Let and , then what is AB equal to?

• (A)
• (B)\begin{bmatrix}ax+hy+gz\\hx+by+fz\\z\end{bmatrix}
• (C)\begin{bmatrix}ax+hy+gz\\hx+by+fz\\gx+fy+cz\end{bmatrix}Correct
• (D)[ax+hy+gz\ \ \ hx+by+fz\ \ \ gx+fy+cz]