As longitudinal wave travel particles in the medium are pushed together and then pulled apart. we call this

compression and rarefaction

Explanation:

This kind of wave is called a longitudinal wave and an example of such a wave is a sound wave.  The center of compression can be analogous to the top of a crest of a transverse wave while the center of the rarefaction would be analogous to the bottom of the trough of a transverse wave.

compression

Explanation:

The part of a longitudinal wave where the particles are more closely pushed together is called a compression.

answer; i believe the correct answer is (anemia);

it is either c or d and i know for sure it is not a or b