$y = a(x+3)(x-4)$ <br> In the quadratic equation above, $a$ is a non zero constant. The graph of the equation in the $xy$-plane, is a parabola with vertex $(c, d)$. Which of the following is equal to $d$ ?

Question

$\begin{array}{1 1} (a)\;10\;a \\ (b)\; 10.25\;a \\ (c)\; 12 \;a \\ (d)\; 12.25\;a \end{array}$