The existence of two different colored complexes of $[Co(NH_3)_4Cl_2]^+$ is due to which of the following?

Consider the following isomerism:
$i$. Ionization
$ii$. Hydrate
$iii$. Coordination
$iv$. Geometrical
$v$. Optical
Which of the above isomerisms are exhibited by $[Cr(NH_3)_2(OH)_2Cl_2]^-$?

Amongst $TiF_6^{2-}$,$CoF_6^{3-}$,$Cu_2Cl_2$ and $NiCl_4^{2-}$,the colourless species are

$Cis-trans$ isomerism is found in square planar complexes of the molecular formula: ($A$ and $B$ are monodentate ligands):

For the octahedral complexes of $Fe^{3+}$ in $SCN^{-}$ (thiocyanato-$S$) and in $CN^{-}$ ligand environments,the difference between the spin-only magnetic moments in Bohr magnetons (when approximated to the nearest integer) is
[Atomic number of $Fe = 26$]

The number of isomers of $[Co(dien)Cl_3]$ is