The correct answer is A. Schottky diode.
A Schottky diode is a type of semiconductor diode formed by the junction of a metal and a semiconductor. It is a fast switching diode with a low forward voltage drop. Schottky diodes are often used in high-speed switching applications, such as power supplies and digital circuits.
A P-N junction diode is a type of semiconductor diode that is formed by the junction of a P-type semiconductor and an N-type semiconductor. It is a two-terminal device that allows current to flow in one direction only. P-N junction diodes are commonly used in rectifiers, amplifiers, and oscillators.
A photodiode is a type of semiconductor diode that is sensitive to light. It is a two-terminal device that converts light into an electrical signal. Photodiodes are commonly used in optical communication, optical sensing, and solar cells.
A tunnel diode is a type of semiconductor diode that exhibits negative differential resistance. It is a two-terminal device that can be used as an amplifier or oscillator. Tunnel diodes are not commonly used in commercial applications.