The threshold voltage or cut-in voltage for Germanium diode is

The correct answer is Option (2) → ~ 0.2 V

The cut-in (threshold) voltage is the forward voltage beyond which the current through a diode rises sharply; below it the applied voltage is still used up in overcoming the barrier potential. Germanium has a smaller band gap (about 0.7 eV) than silicon (about 1.1 eV), so its junction has a lower barrier: the cut-in voltage is about 0.2 V for germanium and about 0.7 V for silicon.

NCERT (2026-27):
p-n Junction Diode Under Reverse Bias – “… After the characteristic voltage, the diode current increases significantly (exponentially), even for a very small increase in the diode bias voltage. This voltage is called the threshold voltage or cut-in voltage (~0.2V for germanium diode and ~0.7 V for silicon diode).”