Fact 1: Plucking a string can cause that string to vibrate.

Fact 2: Nylon string is by far the softest sound on the guitar.

Given the two facts above, answer the question "What do guitars make sound with?" with the following options: 
- friction
 - vibration
 - voltage
 - energy
 - power
 - bamboo
 - mechanical
 - heat energy


 

  vibration       