Optical fibre: It is a very thin fibre made of glass and plastic having a radius of the order of a micrometer (10 m).
It works on the principle of Total Internal Reflection.
It is lightweight, fast, and useful for long-distance data and light transmission with very few losses.
Optical fiber mostly used for communication purposes with negligible loss of energy.
A bundle of such thin fibres forms a light pipe.
EXPLANATION:
The working principle of optical fibers is Total Internal Reflection. So option 3 is correct.
Scattering of light: The phenomenon in which the particles in a colloid scatter the beams of light that are directed at them is called scattering of light.