$(A)$ $\left[ Ni \left( H _{2} O \right)_{2}( en )_{2}\right]^{2+}$
$(B)$ $\left[ Ni \left( H _{2} O \right)_{4}(\text { en })\right]^{2+}$ અને
$(C)$ $\left[ Ni ( en )_{3}\right]^{2+}$
(B) $\left[ Ni \left( H _{2} O \right)_{4}( en )\right]^{2+}$
(C) $\left[ Ni ( en )_{3}\right]^{2+}$
en is SFL (strong field ligand)
As the number of en (strong ligand) increase splitting also increases.
So, $\Delta_{0}$ increases.
i.e. maximum energy will be absorbed in case of option $C.$
So the order is $C\,>\,A\,>\,B$