`CuSO_4` is paramagnetic while `ZnSO_4` is diamagnetic because
A. `Cu^(2+)` ion has `3d^9` configuration while `Zn^(2+)` ion has `3d^(10)` configuration
B. `Cu^(2+)` ion has `3d^5` configuration while `Zn^(2+)` ion has `3d^6` configuration
C. `Cu^(2+)` has half filled orbitals while `Zn^(2+)` has fully filled orbitals
D. `CuSO_4` is blue in colour while `ZnCO_4` is white.
