23. the defect in a crystal which arises due to a vacancy in an otherwise perfect lattice and in it an atom or ion is missing from its normal site of the lattic

23. The defect in a crystal which arises due to a vacancy in an otherwise perfect lattice and in it an atom or ion is missing from its normal site of the lattice is termed as A. It is a B type of defect. Here A and B respectively are: (a) Schottky, Extrinsic point (c) Frenkel, Intrinsic point (b) Schottky, Intrinsic point (d) Frenkel, Extrinsic point