The octahedral complex of a metal ion M^3+ with four monodentate ligands L_1, L_2, L_3 and L_4 absorb wavelengths in the region of red, green, yellow…

The octahedral complex of a metal ion $\displaystyle \mathrm{M}^{3+}$ with four monodentate ligands $\displaystyle \mathrm{L}_1$, $\displaystyle \mathrm{L}_2, \mathrm{~L}_3$ and $\displaystyle \mathrm{L}_4$ absorb wavelengths in the region of red, green, yellow and blue, respectively. The increasing order of ligand strength of the four ligands is :