B
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### 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?

### Choices:
A. vibrations on the ground
B. vibrations of the air
C. seismic waves
D. light waves

### Answer:
