9. A salt, MY, crystallizes in a body-centered cubic structure with a Y⁻ anion at each cube corner and an M⁺cation at the cube center. Assuming that the Y⁻ anions touch each other and the M⁺ cation at the center, andthat the radius of Y⁻ is 158 pm, what is the radius of M⁺?
(A)65.4 pm
(B)116 pm
(C)79.0 pm
(D)41.1 pm
(E)105.3 pm