b
The square planar complex of the type \([Mabcd]^{n±}\), where all four ligands are different, has \(3\) geometrical isomers. But if one of the ligands is ambidentate, then \(2\times3\, = 6\) geometrical isomers are possible. But if two ligands are ambidentate, then \(4\times3\, = 12\) geometrical isomers are possible. In the given example, \(NO_2^-\) and \(SCN^-\) are ambidentate ligands