The potential in depletion layer is due to
a)	Electrons	b)	Holes	c)	Ions	d)	Forbidden band

(c)

The potential in depletion layer is due to ions. It appears as if some fictitious battery is connected across the junction with its negative pole connected to -region and positive pole connected to -region. The potential difference developed across the junction due to migration of majority charge carries in potential barrier.