For the matrix $A$ below, compute the dimension of the null space of $A$, $\dimension{\nsp{A}}$. \begin{equation*} A= \begin{bmatrix} 2 & -1 & -3 & 11 & 9 \\ 1 & 2 & 1 & -7 & -3 \\ 3 & 1 & -3 & 6 & 8 \\ 2 & 1 & 2 & -5 & -3 \end{bmatrix} \end{equation*}