Question

which refers to the density of the mediums particles at the compression of a sound wave?
amplitude
pitch
volume
wavelength

Explanation:

Amplitude is related to the density of particles at compression in a sound - wave. It represents the maximum displacement of particles from their rest position, and at compressions, the particle density is high and related to the amplitude of the wave. Pitch is related to frequency, volume is related to intensity (which is related to amplitude but not the direct measure of particle density at compression), and wavelength is the distance between two consecutive points in phase in a wave.

Answer:

amplitude