The pitch of the sound is determined by its

The pitch of a sound is determined by its frequency. Frequency refers to the number of cycles or vibrations a sound wave completes in a given amount of time. It is measured in hertz (Hz), where one hertz represents one cycle per second.

In general, higher-frequency sounds are perceived as higher in pitch, while lower-frequency sounds are perceived as lower in pitch. For example, a high-pitched whistle produces sound waves with a high frequency, while a low-pitched drum produces sound waves with a low frequency.

Hence, the correct option is "frequency".