The correct option is (b) Frenkel defect is a dislocation defect.
The Schottky defect has some effect on the physical properties of solids such as lower density, lower lattice energy or stability etc.
Frenkel defect is usually favoured by a large difference in the sizes of cations and anions. Cations are small in size than anions.
Frenkel defect is a dislocation defect. A cation moves to another position between two layers.
Trapping of electrons in the lattice leads to the formation of F-centers.
