Here's why:

* The nature of sound: Sound travels as vibrations through a medium. These vibrations cause molecules to bump into each other, transferring energy.

* Density and stiffness: Solids are denser and more tightly packed than liquids. This means the molecules are closer together, allowing for faster energy transfer. Additionally, solids are stiffer, meaning they resist deformation more effectively. This resistance allows for quicker vibrational propagation.

Think of it this way:

* Imagine a line of people holding hands. If you give a quick push to the first person, the energy will travel faster down the line if they are tightly packed and holding hands tightly (like a solid) compared to if they are spaced apart and holding hands loosely (like a liquid).