Step-by-step explanation:
(1) Is referring to Newton's first law, an external force (gravitational force) is applied to frogs motion, thus causing it to deviate from a straight line
(2) is referring to Newton's third law of motion, the action force is done by the ball hitting the ground and the direction is downwards, the reaction force is done by the ground transferring that same force to the ball, acting upwards
(3) I think it's also the first law, the person on a train is showing, the force to keep it at rest, the sudden halt of the train causes a reaction force to act on the person, does making the person move
(4) I think it's both Newton's second law and third law motion.
I hope these helps