A $3\mathrm{.}0-kg$ and a $5\mathrm{.}0-kg$ box rest side$-$by$-$side on a smooth, level floor. A horizontal force of $32$ N is applied to the $3\mathrm{.}0-kg$ box pushing it against the $5\mathrm{.}0-kg$ box, and, as a result, both boxes slide along the floor. How large is the contact force between the two boxes?

$24$ N

$20$ N

$0$ N

$12$ N

$32$ N