Sound speed increases with medium density and particle proximity

Steps:

• Sound is a mechanical wave requiring particles to vibrate and transmit energy.
• Speed depends on how closely packed and elastic particles are in the medium.
• Compare media: gases have sparse particles, liquids denser, solids most compact.
• Thus, solids enable fastest transmission due to minimal distance between particles.

Why D is correct:

• In solids, particles are tightly bound, maximizing elasticity and minimizing propagation delay per the wave speed formula v = √(E/ρ), where E is elastic modulus and ρ is density.

Why the others are wrong:

• A: Sound cannot travel in a vacuum as no particles exist to carry vibrations.
• B: Gases have widely spaced particles, slowing wave transmission.
• C: Liquids are denser than gases but less rigid than solids, resulting in intermediate speed.

Final answer: D