Which best explains why sound travels fastest through a solid? a. sound is a mechanical wave, so closer molecules in the medium cause energy to transfer faster. b. sound is a mechanical wave, so if the volume of the medium is greater, more energy is transferred. c. sound is an electromagnetic wave, so the medium does not affect the speed. d. sound is an electromagnetic wave, so a greater amplitude results in a greater speed.

A. Sound is a mechanical wave, so closer molecules in the medium cause energy to transfer faster.

Explanation:

In a mechanical wave (such as sound), the transfer of the energy occurs due to the oscillations of the molecules: by colliding with the other molecules close to them, they transfer energy.

From this mechanism, we can easily understand that the closer the molecules are, the more efficient this process is, and therefore the faster the energy is transferred. In solids, molecules are very closed to each other (much more than in liquids or gases), so the sound wave can propagate faster and the energy transfer also occurs faster.