The correct answer is destructive interference.
Unavoidably, some of the waves are going to meet with each other or are going to cross over, and when they do, the reaction between the waves is called interference.
When the troughs or crests of two interfering waves encounter with each, their amplitudes get add together, this phenomenon is called constructive interference.
On the other hand, when the crest of one wave encounters with the trough of another wave, the reverse takes place, and it is known as destructive interference. When the trough and crest of two interfering waves encounter with each, one amplitude gets subtracted from the other.
