$M = \begin{pmatrix} 1 & 3 \\ 2 & 4 \end{pmatrix}$

$M = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}$

$M = \begin{pmatrix} 4 & 2 \\ 6 & 4 \end{pmatrix}$

$M = \begin{pmatrix} 1 & 4 \\ 2 & 6 \end{pmatrix}$