An unbiased p-n junction has holes diffusing from p-region to the n-region because: 

Concept:

p-type semiconductor has following characteristics:

• A p-type semiconductor is an intrinsic semiconductor doped with boron or indium.

• The majority of carriers in p-type semiconductors are holes.

• Electrons are minority carriers in a p-type semiconductor.

• In a p-type semiconductor, the hole density is much greater than the electron density.

• The acceptor energy level of the p-type is close to the valency bond and away from the conduction band.

• In an n-type semiconductor an intrinsic semiconductor doped with phosphorus or antimony as impurity.

n-type semiconductor has following characteristics:

• The majority of charge carriers in n-type semiconductors are electrons.

• Holes are minority carriers in a n type semiconductor.

• In the n type of semiconductor, the electron density is much greater than the hole density.

• The donor energy level of n-type is close to the conduction band and away from the valency band.

The diffusion of charge carriers across a junction takes place from the region of higher concentration to the region of lower concentration. In this case, the p-region has greater concentration of holes than the n-region. Hence, in an unbiased p-n junction, holes diffuse from the p-region to the n-region.

Hence, the correct answer is Option-2-hole concentration in p-region is more compared to the n-region.