Concept:Rainbow formation is explained by the splitting of white light into its component colours.
Explanation:When sunlight passes through water droplets in the atmosphere, each droplet acts like a tiny prism.
The light is refracted as it enters the droplet, then reflected inside, and refracted again as it leaves.
This process separates white light into its seven constituent colours because each colour has a different wavelength.
This separation of light into colours is called dispersion.
Therefore, the main phenomenon responsible for rainbow formation is dispersion.
Answer:D. dispersion