Which of the Following Contributes) to the Arrangement of Ions

Multiple Choice

Which of the following contributes) to the arrangement of ions in the unit cells of an ionic solid?
I.the empirical formula
II.the relative radii of the ions
III.the shape of polyatomic ions

A) I and II only
B) II and III only
C) I and III only
D) I only
E) I, II, and III