Answer:
10 Newtons to the left.
Explanation:
From the attached figure, it can be seen that the force acting towards right and left are [tex]F_r\ and\ F_l[/tex] such that,
Let us consider the force acting towards right are positive and negative for towards left.
[tex]F_r=10\ N[/tex]
[tex]F_l=-20\ N[/tex]
Let F is the net force acting on the box. It is equal to :
[tex]F=F_l+F_r[/tex]
[tex]F=-20+10[/tex]
F = -10 N
So, the resultant force acting on the box is 10 N and it is acting towards left. Hence, the correct option is (c).