Which Answer Best Accounts for the Na⁺ Ions Present in the NaCl

Which answer best accounts for the Na⁺ ions present in the NaCl unit cell?

A) 1 center atom + 1/8 * 24 corner atoms
B) 1 center atom + 1/2 * 6 face atoms
C) 1 center atom + 1/8 * 8 corner atoms
D) 1 center atom + 1/4 * 12 edge atoms
E) 1/8 * 8 corner atoms + 1/2 * 6 face atoms