Sound cannot travel through:

The correct answer is Option (4) → Vacuum

Sound is a mechanical wave: it travels as vibrations passed from one particle of a medium to the next. A vacuum has no particles to vibrate, so sound cannot pass through it; this is why astronauts in space talk by radio.

Air, water and steel all carry sound, and it travels faster as the medium gets denser and stiffer: about 343 m/s in air, about 1,500 m/s in water and about 5,000 m/s or more in steel.