Correct Answer is: (d)
Sound is transmitted by particles (atoms or molecules) in a solid, liquid or gas colliding with each other. It is a wave which is created by vibrating objects and propagated through a medium (solid, liquid or gas) from one location to another. A vibrating source can be sound coming from a drum, speaker of a radio, the mouth of a person (vocal cord), a car engine, a plane above the sky and so on. Although sound is commonly associated in air, sound will readily travel through many materials that are solid, liquid and gas.
