If $\begin{vmatrix} x^2+x & x+1 & x-2 \\2x^2+3x-1 & 3x & 3x-3 \\ x^2+2x+3 & 2x-1 & 2x-1 \end{vmatrix}=ax-12$ then 'a' is equal to :

Question

$\begin{array}{1 1} 12 \\ 24 \\ -12 \\ -24 \end{array} $