Answer:
The correct answer is - the sound waves make vibration that travels through the string.
Step-by-step explanation:
When an individual person talks into your paper cup telephone the person on the other end can feel the bottom of their cup vibrate. The sound waves create vibration go through the string that travels through the string to the end of the cup where vibrations can feel.
The sound waves are longitudinal waves that move or travel through different mediums like air, solid, or gas. The waves create vibration in the particles.
You could create a paper cup telephone but instead of using string, test out different materials and see if those materials will allow sound vibrations to travel through them