Select the correct answer.

What is this expression in simplest form?

$12$x$24$x$2$x

A$.$

$3$x$82$x$($x$2)$

B$.$

$4$x$+92$x$($x$2)$

C$.$

$4$x$72$x$($x$2)$

D$.$

$12$x$($x$2)$