c
\(Cu^{2+}\) forms complexes with the same magnetic moment and geometry irrespective of the nature of ligand. It can be explained by electronic configuration.

It has \(9\) electrons in \(3d\) shell. Hence any incoming ligand whether it is strong or weak will result in the formation of same geometry (if number of ligands is same) because any ligand can do nothing with this unpaired \(e^-\) in \(3d\) shell. Moreover, the complex formed will have same magnetic moment due to this unpaired \(e^-\).