A p-n junction can act basically as

The correct answer is Option (3) → Both Half as well as full wave rectifier

A p-n junction conducts when it is forward biased and blocks the current when it is reverse biased, so it passes current in one direction only. This is what makes it a rectifier.

With a single junction diode in series with the load, only one half of each ac cycle is passed, which is a half-wave rectifier. Two junction diodes (with a centre-tapped transformer) or four junction diodes (in a bridge) pass both halves of the cycle in the same direction through the load, which is a full-wave rectifier.

So the p-n junction can serve as the basic element of both kinds of rectifier.

NCERT (2026-27):
Application of Junction Diode as a Rectifier – “… Since the rectified output of this circuit is only for half of the input ac wave it is called as half-wave rectifier. The circuit using two diodes, shown in Fig. 14.19(a), gives output rectified voltage corresponding to both the positive as well as negative half of the ac cycle. Hence, it is known as full-wave rectifier.”