The correct option is B does not change
Frenkel defect is the defect which is created when an ion leaves its appropriate site in the lattice and occupies an interstitial site. A hole or vacancy is thus produced in the lattice.
Frenkel defect is exhibited in ionic compounds in which the radius ratio is low. The cations and anions differ much in their sizes and the ions have low co-ordination numbers. Examples are ZnS, AgBr, AgI, AgCl.
Consequences of Frenkel defect:
1. The closeness of like charges tends to increase the dielectric constant of the crystal.
2. The crystal showing a frenkel defect conducts electricity to a small extent by ionic mechanism.
3. The density of the crystal remains the same.