The answer is indeed letter A) Laws of Motion.
The first Law of Motion is called the Law of Inertia and it states: every object in a state of uniform motion will remain in that state unless an external force acts on it. This law had at first been hinted by Galileo, but was properly developed by Newton.
The second Law of Motion states: force equal mass times acceleration.
The third Law of Motion is the conservation of momentum. It states that, for every reaction, there is an equal and opposite reaction.
Force is the interaction between two objects. If a person sits on a chair, for instance, they exert a downward force on the chair. The reaction is the upward force the chair exerts on their body.
