For what values of $k$ will the equation $9x^2+3kx+4=0$ have real roots?

Question

$\begin{array}{1 1}(A) \; k\leq -4 \text{ or } k\geq 4\\(B)\; k < -4 \text{ or } k > 4\\(C)\;k\geq -4 \text{ or } k\leq 4 \\(D)\;k > -4 \text{ or } k < 4\end{array}$