Which of the following descriptions about `[FeCl_(6)]^(4-)` is correct about the complex ion ?
A. `sp^(3) d` , inner orbital complex , diamagnetic
B. `sp^(3) d^(2)` , outer orbital complex , paramagnetic
C. `d^(2) sp^(3)` , inner orbital complex , paramagnetic
D. `d^(2) sp^(3)` , outer orbital complex , diamagnetic .