In the depletion layer of a reverse biased p-n junction, the :

The correct answer is Option (2) → potential is maximum

Note: The given answer is as per the official NTA Answer Key. However, none of the given options appears to be correct: the electric field is maximum at the junction, as explained below.

The depletion layer holds only fixed ions: negative acceptor ions on the p-side and positive donor ions on the n-side. Their electric field points from the n-side to the p-side, and reverse bias widens the layer and raises the potential barrier.

Inside the layer the field is largest at the junction and falls to zero only at the two edges, so it is not zero (Option 4). The potential rises steadily from the p-side edge to the n-side edge, so it is neither zero (Option 1) nor maximum inside the layer. The small reverse current is a drift current of minority carriers, so the drift current is not zero (Option 3).

It seems that NTA has read "potential is maximum" as the potential barrier being large, which reverse bias makes larger.

NCERT (2026-27):
p-n Junction Diode Under Reverse Bias – “When an external voltage (V) is applied across the diode such that n-side is positive and p-side is negative, it is said to be reverse biased [Fig.14.15(a)]. The applied voltage mostly drops across the depletion region. The direction of applied voltage is same as the direction of barrier potential. As a result, the barrier height increases and the depletion region widens due to the change in the electric field.”