ANS:C - high resistance when reverse biased and low resistance when forward biased

In reverse bias as -ve voltage of the battery is connected with P side of the diode, it attracts the majority charge carrier hole and left the -ve ion across the junction of P side of Diode. Similarly, the +ve supply of battery attracts majority carrier electron and left +ve ion across the junction of n side of the diode. So the depletion region increases and more energy is required to make the diode is operational as the resistance is very high.

In the Forward bias as the depletion region decreases, resistance becomes low.