Concept:Rainbow formation involves dispersion of white light together with refraction and total internal reflection inside water droplets.
Explanation:When sunlight enters a raindrop, it is first refracted at the air-water surface.
During this refraction, the white light is dispersed into its component colours because each colour has a different wavelength.
The dispersed light then strikes the back of the droplet and undergoes total internal reflection.
Finally, the reflected light leaves the droplet through the front surface, where it is refracted again as it passes from water to air.
Ordinary reflection from the droplet surface is not the key process; the crucial reflection is total internal reflection inside the droplet.
Thus, the required phenomena are dispersion, total internal reflection, and refraction.
Answer:C. (ii), (iii) and (iv) only