$(3$ pts $)$ A $4\mathrm{.}00-kg$ projectile is fired at an angle of $20\mathrm{.}0$ above the horizontal. What is the magnitude of the force exerted on the projectile when it is at the highest position in its trajectory? $($assume air resistance is negligible$)$

$($a$)0$ N

$($b$)9\mathrm{.}80$ N

$($c$)19\mathrm{.}6$ N

$($d$)29\mathrm{.}4$ N

$($e$)39\mathrm{.}2$ N