Final answer:
Newton's third law of motion states that for every action, there is an equal and opposite reaction.
Step-by-step explanation:
Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert a force back on the first object of the same magnitude but in the opposite direction. So the answer is C. Action = Reaction.