The reflection of sound.

• A. Whisper
• B. Echo
• C. Noise
• D. Chorus

Answer: (B)

When sound bounces off a surface and comes back to your ears, you’re hearing an echo. This happens because sound waves travel through the air, hit a hard, smooth surface, and reflect rather than be absorbed. The reflected waves then travel back to you, arriving a moment later, so you perceive the same sound again as a distinct repetition. For an echo to be noticeable, the surface has to be far enough away that there’s a clear delay between the original sound and the reflected sound. Think of shouting in a canyon or in a large empty hallway. The other options—whisper, noise, or chorus—describe different kinds of sounds, not the reflected sound you hear after it bounces off a surface.