Katrina pushes off a flat sidewalk on her new skateboard.
What causes her to move?
A.
The force of her push overcomes the forces of gravity and friction.
B.
The force of gravity overcomes the forces of her push and friction.
C.
The force of friction overcomes the normal force of the skateboard and the force of gravity.
D.
The normal force of the skateboard overcomes the force of her push and the force of gravity.