Answer: (b) i, ii & iii only
To travel, sound required a medium. Sound cannot travel in a vacuum because there is no medium to transmit sound waves.
- Sound needs a material medium for its propagation like solid, liquid or gas to travel because the molecules of solid, liquid and gases carry sound waves from one point to another.
- Sound cannot progress through the vacuum because the vacuum has no molecules which can vibrate and carry the sound waves.