Explanation:

- Sound is a mechanical wave that needs a medium to travel.

- It cannot travel through a vacuum because there are no particles to vibrate. Therefore, Option:2 Vacuum is incorrect.

- Sound travels faster through media with higher densities and low compressibility.

- Solids typically have closely packed molecules, so sound travels fastest through them. ? Option:3 Solid: Correct Answer

- In liquids, molecules are less tightly packed than solids but more than gases, so sound travels slower than in solids but faster than in gases.

- Gases have widely spaced particles, making sound travel slowest in this medium. Option:1 Gas is slower than liquids and solids.