Through which of the following media does sound travel the fastest?
A. A crowded room
B. Ground
C. Interplanetary space
D. An empty room
B
Since sound is a mechanical wave, sound cannot travel through a vacuum. Thus answer C is not possible. In a crowded or empty room, sound is traveling through the air, a gaseous medium. The ground is a solid medium. Since mechanical waves travel fastest through solids, answer B is the best choice.