Which one of the following compounds shows both, Frenkel as well as Schottky defects?

It is known that Schottky defects arise due to missing of ions from their lattice point and Frenkel defects arise when the missing ions occupy the interstitial sites.

Now for the case of $\mathrm{AgBr}$, we know that the radius of $\mathrm{AgBr}$ being intermediate, hence it shows both Frenkel and Schottky defects.

The major defect that occurs in $\mathrm{AgBr}$AgBr is the Frenkel defect. It has ccp lattice, The larger halide ions are arranged in a cubic close-packing, while the smaller silver ions fill the octahedral gaps between them, giving a 6-coordinate structure where a silver ion Ag⁺ is surrounded by 6 Br⁻ ions, and vice versa.

 Ag moves from octahedral to tetrahedral sites thereby causing only cations to precipitate.

Also, Schottky defect in AgBr is exhibited due to precipitation of both cations and anions. Finally, the Ag⁺ ion is small in size in AgBr and therefore when removed from lattice point it can occupy interstitial site and hence show both Frenkel and Schottky defects.