If the doping level in a crystal diode is increased, the width of depletion layer___________

The more doped a semiconductor, the more conductive and less resistive it becomes and hence reduction or decrease in the depletion layer. Since the width of the depletion layer is inversely proportional to the doping concentration hence the width will decrease when the doping is increased.

Decreases the option is wrong

Since the width of the depletion layer is inversely proportional to the doping concentration hence the width will decrease when the doping is increased.

Doping level is inversely proportional to depletion width hence as doping level is increased then the width will decrease...