Which of the following is the sound of single frequency?

Correct option is D

The correct answer is (d) Tone.
· A tone is a sound that has a single frequency.
· It is a pure sound with no harmonics or variations in frequency, unlike other types of sounds that may consist of multiple frequencies.
Other options explained:
· Note: A note usually refers to a sound with a specific pitch, but it can contain multiple frequencies, including harmonics, making it different from a pure tone.
· Noise: Noise is an irregular and chaotic combination of sounds at multiple frequencies, lacking the regularity of a single frequency.
· Timber or quality of sound: Timbre refers to the quality or color of sound, determined by the mixture of multiple frequencies, not just one.