On connecting a device X in a series circuit with a battery and a resistor, a current passes through the circuit. On reversing the polarity of the battery, the current in the circuit drops to almost zero. The device X may be a

p-n junction diode

The correct answer is Option (3) → p-n junction diode **

When the current flows in one direction but drops to almost zero when the polarity is reversed, the device allows current in only one direction.

This is the characteristic behavior of a p–n junction diode (forward-biased conduction and reverse-biased blockage).

Correct option: p–n junction diode