Using a motion sensor$,$ Susana finds that the acceleration of a $4-$kg rock that has been dropped from the roof of a building is $6$ m$/$s$2.$ She concludes that the magnitude of force of air resistance acting on the rock is approximately

Group of answer choices

$39\mathrm{.}2$ N$.$

$15\mathrm{.}2$ N$.$

None of these is correct.

$9\mathrm{.}81$ N$.$

$24\mathrm{.}0$ N$.$