The correct option is
A of mixture of several frequencies
Explanation for the correct option
Option (A)
- Sound is one type of longitudinal wave.
- When sound waves of different frequencies are superimposed, then notes produce.
- So, a note is a sound wave that produces from a mixture of several sound waves.
Explanation for the incorrect options
Option (B)
- The note is a sound of a mixture of two frequencies only, this statement is not true always. Not only two but several frequencies of sound waves can also produce notes.
Option (C)
- A sound of a single frequency is a tone. The sound produced from a string of a guitar is a tone.
Option (D)
- At resonance, the superposition or mixture of sound waves (note) is pleased to hear.
Hence, option (A) is correct.