Answer: C. -12 newtons
Explanation: Since, the block is in static equilibrium,
the net force on the block is zero i.e. balance forces are acting on the block.
In the horizontal direction,
force applied+force due to friction = 0
20 N + (-20N) = 0
In the vertical direction as well, net force is zero:
Force due to gravity + force exerted by the ground = 0
12 N + force exerted by the ground = 0
⇒force exerted by the ground = 0 -12 N = -12 N
Thus, the correct option is C. -12 N where negative sign means that the direction of the force due to ground is opposite to the force of gravity.
