$\text{If } \begin{vmatrix} x&2 \\ 18&x \end{vmatrix} = \begin{vmatrix} 6&2 \\ 18&6 \end{vmatrix}$, then $x$ is equal to:

Question

$\begin{array}{1 1} 6 \\ \pm 6 \\ -6 \\ 0 \end{array}$