Option (A ) is correct.
Step-by-step explanation:
susan is moving with constant velocity, so both the direction and magnitude of the velocity remains same. so the acceleration of susan =0. This is because an object gets accelerated when either the magnitude or direction of the speed changes.
now the force is given by

F= force
m= mass
a= acceleration
Here a =0
so F= 0
so the net force on susan is zero.