Here's a problem to solve: During a sporting event, a referee uses a whistle to alert the teams to start and stop playing. What causes the sound from the referee's whistle to travel in all directions?

Among the 4 following options, which is the correct answer?

- A: vibrations on the ground
 
- B: vibrations of the air
 
- C: seismic waves
 
- D: light waves
 