Newton's third law states that, for every action force there is an equal and opposite reaction force.
Action and reaction forces acts on two different bodies.
In case of rocket propulsion, the action force is due to the exhaust of gases pushing downward on the earth and due to the reaction force the rocket moves upwards in the space.
The answer is A. Newton's third law of motion states that for every action, there is an equal and opposite reaction. A rocket exerts a large force on the gas that is in the rocket chamber (action). The gas thus exerts a large reaction force forward on the rocket (reaction). The large reaction force is called thrust.
A force is a push or pull upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects.
