LED is a p-n junction diode which isA: forward biasedB: either forward or reverse biasedC: reverse biasedD: neither forward biased or reverse biased

The correct answer is A: forward biased.

LED stands for Light-Emitting Diode, and it is indeed a p-n junction diode. When the LED is forward biased, it means that the positive terminal of the power supply is connected to the p-side of the diode and the negative terminal is connected to the n-side. This forward biasing allows current to flow through the diode.

In this configuration, when electrons and holes recombine at the junction, the excess energy is released in the form of light. This is the fundamental principle behind the emission of light in an LED. Therefore, LEDs are typically operated in a forward-biased mode to emit light.