A $15-$g bullet is shot vertically into an $2-$kg block. The block lifts upward $8\mathrm{.}0$ mm $($see the figure$).$ The bullet penetrates the block and comes to rest in it in a time interval of $0\mathrm{.}0010$ s $.$ Assume the force on the bullet is constant during penetration and that air resistance is negligible. The initial kinetic energy of the bullet is closest to

$21$J

$0\mathrm{.}0012$ J

$0\mathrm{.}16$ J