In a CsCl type crystal:

• A

  Cs⁺ ions form a simple cubic lattice and Cl^- ions also form a simple cubic lattice 

• B

  Cl^- ion occupies body centre of Cs⁺ ion unit cell

• C

  Cs⁺ ion occupies body centre of Cl^- ion unit cell 

• D

  it is impossible for Cl^- ion to occupy body centre of Cs⁺ ion unit cell because the body centre void of Cs⁺  is smaller than the Cl^- ion size