If an Ionic Compound with the Formula MX₂ Forms a Face-Centered

If an ionic compound with the formula MX₂ forms a face-centered cubic unit cell with the cations (M²ⁿ⁺) at the lattice points,the anions (X^n-) will occupy

A) all of the tetrahedral holes in each unit cell.
B) half of the tetrahedral holes in each unit cell.
C) all of the octahedral holes in each unit cell.
D) the center of each face in each unit cell.
E) the cubic hole in the center of the each unit cell.