Fact 1: Blowing air into a whistle causes air to vibrate inside the whistle.

Fact 2: An ocarina is a multiple-tone whistle.

Given the two facts above, answer the question "What happens to the air inside an ocarina when you blow into it?" with the following options: 
- It expands
 - evaporation
 - moves
 - waves
 - Temperature
 - vibrates
 - It decreases
 - friction


 

      vibrates   