vibrations on the ground vibrations of the air seismic waves light waves
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: 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?
Possibilities:
- vibrations on the ground
- vibrations of the air
- seismic waves
- light waves

vibrations of the air