Pitch increases with the increase in _______ of a vibrating body.
A.Frequency
B.Amplitude
C.Loudness
D.length

Hint: Here,make use of the concept which says that the pitch of a sound is primarily related to the frequency of the sound waves.


Complete step-by-step solution:
Sound is produced when a body vibrates and it reaches us through the vibrations of the particles of the surrounding medium.
Pitch is a characteristic of sound by which an acute note can be distinguished from a flat note of the same loudness.
Pitch of a note depends on its frequency. Two notes sounded on the same instrument will differ in pitch when their vibrations are of different frequencies, even if they have the same amplitude. More the frequency of a wave higher is the pitch and less the frequency of a wave, lower is the pitch.
So, pitch increases with increases in frequency of a vibrating body.
Loudness of a sound is affected by the amplitude of the wave, but it does not affect the pitch of a sound. Two sources having the same loudness may have different pitch.

Therefore, option A. is the correct answer.

Additional information:
If the pitch is high, the sound is shrill and if the pitch is low, the sound is flat.
A voice of a woman is usually of a higher pitch than that of a man.
In a string instrument, such as violin, guitar, the frequency of vibrations of a string depends on the thickness and tension of the string. A note of higher pitch can be obtained by vibrating the string under high tension or by vibrating a thinner string.


Note: Pitch is not the same as frequency. Pitch is of a subjective nature, it differs from person to person depending on the sensation perceived by a listener. However, frequency is a measurable quantity and depends on the source of the sound.