The order of energy absorbed which is responsible for the color of complexes

(A) ${\left[\mathrm{Ni}{\left({\mathrm{H}}_2\mathrm{O}\right)}_2(\mathrm{en}{)}_2\right]}^{2+}$

(B) ${\left[\mathrm{Ni}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4\left(\mathrm{en}\right)\right]}^{2+}$ and

(C) ${\left[\mathrm{Ni}{\left(\mathrm{en}\right)}_3\right]}^{2+}$ is

The complexes with strong filed ligands absorbs the highest energy light than complexes with weak field ligands.

Ethylene diamine(en) is strong field ligand and ${\mathrm{H}}_2\mathrm{O}$ is the weak field ligand.

Hence, the correct order of energy absorbed is 

${\left[\mathrm{Ni}{\left(\mathrm{en}\right)}_3\right]}^{2+}>{\left[\mathrm{Ni}{\left({\mathrm{H}}_2\mathrm{O}\right)}_2{\left(\mathrm{en}\right)}_2\right]}^{2+}>{\left[\mathrm{Ni}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4\left(\mathrm{en}\right)\right]}^{2+}$