The correct statement in the following is

Options

A. The ionic crystal of AgBr has Schottky defect
B. The unit cell having crystal parameters, `a=bnec,alpha=beta=90^(@),gamma=120^(@)` is hexagonal
C. In ionic compounds having Frenkel defect the ratio `(r_+)/(r_-)` is high
D. The coordination number of `Na^(+)` ion in NaCI is 4

Answer

B