Concept:The speed of sound is lowest in gases and highest in solids because it depends on the spacing and elasticity of particles.
Explanation:Sound travels as vibrations passing from one particle to another.
In air, the particles are far apart and the medium is less elastic.
Hence, sound travels more slowly in air than in water or solids.
In brass and wood, which are solids, particles are tightly packed and transmit vibrations faster.
Water, being a liquid, allows sound to travel faster than in air but slower than in most solids.
Therefore, among the given media, air has the least speed of sound.
Answer:A. Air