A horse pulls a Wagon forward. what is the equal and opposite force for the force of the horse pushing down on the ground as described by newtons third law?

A. Grounds friction pushes forward on the horse’s hooves
B. Horses force of gravity pulls up on earth
C. Ground pushes up on the horses hooves
D. Earth’s force of gravity pulls down on the horse.

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.