Which feature of a soundwave is related to pitch

loudness

Explanation:

both loudness and pitch are determined by intensity of a sound wave, though pitch has another factor known as frequency

Frequency

Explanation:

As we know that the characteristics of sound is as following

Loudness : loudness of sound depends on the amplitude of sound so increasing the loudness will cause the amplitude to increase.

Quality of sound : Quality of sound depends on the type of waveform. For different waveform the quality of sound is also different.

Pitch of sound : Pitch depends on the frequency of the sound which means if the frequency of sound is more then its frequency will be more

the correct answer will be

Frequency