Destructive interference in which waves cancel each other out is depicted in region X,Y and Z.
<u>Explanation:</u>
Interface is the particle property of light waves. When incident light beam is made to pass through holes, the waves will combine either constructively or destructively. Constructive interference means the waves having same phase will get added so they will increase in amplitude. While destructive interference means the waves combining have different phases like crests and troughs. So they undergo decrease or complete vanishing of amplitude.
When waves combine in constructive interference, they form bright white light and when they combine in destructive interference, they form dark black light. So the regions X, Y and Z are shown as dark black colors in the diagram, so these regions represent destructive interference in which waves cancel each other out.
