Q$\mathrm{.}3)$ All the forces acting on a particle situated at the point of origin of a two$-$dimensional reference frame. One force has magnitude of $20$ N acting in the positive $\backslash ($ x $\backslash )$ direction. Where as the other has a magnitude of $10$ N at an angle of $\backslash (120^\{\backslash$circ$\}\backslash )$ with force directed away from the origin with respect to the positive direction to the direction of $20$ N : The value of the resultant force, R $,$ will be $[2$ marks$]$

$($A$)18$ N

$($B$)20$ N

$($C$)15$ N

$($D$)21$ N