Option 1: Frequency - Correct answer. In the context of sound waves, frequency refers to the number of cycles of a wave that pass a certain point in a specific unit of time. The unit of frequency is the Hertz (Hz). Frequency is directly linked to the pitch of the sound: higher frequency leads to a higher pitched sound while a lower frequency leads to a deeper or lower pitched sound.

Option 2: Amplitude - This represents the size or magnitude of the sound wave. In simpler terms, it refers to how `loud` or `soft` the sound is. Changes in amplitude do not affect the pitch of the sound.

Option 3: Wavelength - This represents the length of one complete wave cycle. While wavelength is inversely related to frequency, it doesn`t directly determine the pitch of the sound.

Option 4: Intensity - It is the amount of energy carried by the wave per unit of time across a surface. Like amplitude, it is associated with the loudness of the sound, not the pitch.

In summary, frequency plays a key role in determining the pitch of a sound wave, whereas amplitude and intensity influence the loudness and wavelength influences the wave cycle.