When a CD (Compact Disc used in audio and video systems) is seen in sunlight, rainbow like colours is seen. This can be explained on the basis of the phenomenon of

1. A Compact Disc (CD) has a surface with billions of small pits arranged in spiral tracks. 2. When sunlight (which is white light, a mixture of different colors) falls on the CD surface, the regularly spaced tracks act like a diffraction grating. 3. Diffraction causes the white light to split into its constituent colors (like a prism), creating the observed rainbow-like colours. This phenomenon is called iridescence. 4. Reflection is also involved, as the light bounces off the CD surface to reach the observer's eye. 5. While some light might pass through the CD (transmission), the rainbow effect seen from the surface is primarily due to reflection and diffraction. Option D includes refraction, which is bending of light when passing through a medium, less relevant here than diffraction from the surface structure. Option A correctly identifies the key phenomena responsible for the colours seen.