Concept:Sound is a mechanical wave, so its speed depends on the medium through which it travels.Explanation:Sound travels fastest in solids because their particles are closely packed.Among the given options, steel is a solid.The speed of sound in steel is about 5960Â m/s.It is about 1497Â m/s in water and 344Â m/s in air.Sound cannot travel in vacuum because it needs a material medium.Answer:Steel