Which of the following expression is correct for packing fraction of NaCl if the ions along with face are diagonally removed?

Options

A. `(13/3 pir_-^3 + 16/3 pir_+^3)/(8(r_+ + r_-)^3)`
B. `(13/3 pir_-^3 + 4/3 pir_+^3)/(8(r_+ + r_-)^3)`
C. `(16/3 pir_-^3 + 13/3 pir_+^3)/(8(r_+ + r_-)^3)`
D. `(4/3 pir_-^3 + 13/3 pir_+^3)/(8(r_+ + r_-)^3)`