$\left[\mathrm{Cr}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]{\mathrm{Cl}}_3$ and $\left[\mathrm{Cr}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4{\mathrm{Cl}}_2\right]\mathrm{Cl}.{\mathrm{H}}_2\mathrm{O}$ are hydrate isomers. Their colors are respectively

It is given to find out the colors of ${\displaystyle \left[Cr{\left(H_{2}O\right)}_6\right]C{l}_3}$ and ${\displaystyle \left[Cr{\left(H_{2}O\right)}_{4}C{l}_2\right]Cl.H_{2}O}$. 

Hydrate isomerism is a kind of ionization isomerism. 
In this, compounds have different no. of solvent molecules bonded to the metal ion.

Explanation

Different numbers of water molecules are present in the coordination sphere and the ionization sphere of the chemicals in question.
As a result, they show hydrate isomerism.

Hence the correct answer is A)violet and green