Two waves travel through each other, and a crest forms with an amplitude smaller that either original waves. What has happened?

This is what I think it is, correct me if I'm wrong. Answer is stated below:

Explanation:

Destructive Interference

Two waves combine to form a wave with a smaller amplitude than either the original wave. Destructive interference can occur when the crest of one wave overlaps the trough of another wave. If the crest has a larger amplitude than the trough of the other wave, a part of it remains.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.