Which phenomenon is responsible for the glittering of a diamond?

What is the phenomenon responsible for the twinkling of stars in the night sky?

The Sun appears reddish during sunrise and sunset. The phenomenon in optics which is responsible for this appearance of the Sun is

The formation of glittering colours in thin foam of soap is the result of which of the following phenomenon –

Rainbow is produced when sunlight falls on drops of rain. which of the following physical phenomena are responsible for this?

Which one of the following phenomenon is used in optical fibres?