Correct option is A
A laser diode is the best source of light for fiber optic communications involving large distances and high speed transmission.
Explanation:
Laser diodes: Laser diodes are single wavelength light sources that travel smoothly with little dispersion. This makes them ideal for long-distance communication.
PIN diodes: PIN diodes are used as photodetectors in fiber optic network cards and switches. They convert light energy into electrical energy.
LEDs: LEDs are used in optical fiber communication applications for distances of a few kilometers and bit rates up to about 1 Gbit/s
