During science class, Ben and Dylan had to set up a demonstration to model one of Newton's laws. This is a photo of their demonstration. When Ben hit the index card with his finger, the penny fell into the cup. What does the students' demonstration illustrate?
A) A force causes a change in velocity and likewise a change in velocity generates a force. 2nd Law of Motion
B) An object subjected to an external force will accelerate and that the amount of the acceleration is proportional to the size of the force. 2nd Law of Motion
C) An object at rest stays at rest and an object in motion stays in motion at the same speed and in the same direction unless acted upon by an unbalanced force. 1st Law of Motion
D) For every action in nature there is an equal and opposite reaction. In other words if object A exerts a force on object B, then object B also exerts an equal force on object A. 3rd Law of Motion

First Law of Motion : An object at rest remains at rest and an object in motion remains in motion at the same speed and in the same direction unless an external force is applied to it and changes its state of motion.

Newtons first law of motion is also known as law of inertia.

For example : The motion of a kite when the wind changes.

Tightening of the seat belts in a car when it stops quickly.

In the demonstration, penny remains at rest when external force is applied then the penny falls into the cup.

Thus, the students' demonstration illustrate the 1st Law of Motion.