Which of the following statements is true about the consequences of Schottky and Frenkel defects? (A) The electrical conductivity of the crystal decreases. (B) Density of the crystal increases in case of the crystals having Schottky defects. (C) The density of the crystal exhibiting frenkel defect is less as compared to that of perfect crystal. (D) Frenkel defects tend to increase the dielectric constant of the crystals.