# 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 and blue respectively .The increasing order of ligand strength of the four ligands is :

$(a)\;L_{4} < L_{3} < L_{2}< L_{1} \qquad(b)\;L_{1} < L_{3} < L_{2} < L_{4} \qquad(c)\;L_{3} < L_{2} < L_{4} < L_{1} \qquad(d)\;L_{1} < L_{2} < L_{4} < L_{3}$