Answer:
The two forces in each pair act in opposite directions. (A) Newton's third law.
Step-by-step explanation:
Newton's third law states that for every action, there is an equal and opposite reaction. This means that if object A exerts a force on object B, object B simultaneously exerts an equal force in the opposite direction on object A. The forces always occur in pairs, and their magnitudes are equal. For example, if you push against a wall with a force, the wall exerts an equal force back on you.
This law is fundamental in understanding interactions between objects and is crucial in explaining phenomena like the motion of rockets, walking, and even the force exerted by a surface to support an object's weight.
Option A is correct.