$C$ is the answer, in $AI12$ matrix will result into the same matrix as $A$ but first column will be exchanged with second column.
$A$ matrix:
$a$ $b$ $c$
$d$ $e$ $f$
$g$ $h$ $i$
$I12$ matrix
$0$ $1$ $0$
$1$ $0$ $0$
$0$ $0$ $1$
resulted matrix
$b$ $a$ $c$
$e$ $d$ $f$
$h$ $g$ $i$