In $\mathrm{AgBr}$, there can occur

$\mathrm{AgBr}$ has both schottky and frenkel defects.  In general, silver haldies show both schottky and frenkel defects. In schottky defect, equal number of cations and anions are missing from crystal lattice. In Frenkel defects cation or anion from ionic solid leaves its regular site and moves to occupy a place between the lattice salt called interstitial position.

Hence the correct answer is (C) both (A) and (B)