d
\(\left[\varepsilon_{\mathrm{a}} \propto \frac{1}{\lambda_{\mathrm{a}}}\right]\)

where \(\varepsilon_{\mathrm{a}} \Rightarrow\) absorbed energy (splitting energy)

\(\lambda_{\mathrm{a}} \Rightarrow\) absorbed wavelength

Presence of \(\mathrm{SFL} \Rightarrow \varepsilon_{\mathrm{a}}(\uparrow) \lambda_{\mathrm{a}}(\downarrow)\)

\(\mathrm{H}_{2} \mathrm{O}<\mathrm{NH}_{3}<\) en ligand strength \(\uparrow\) splitting energy \(\uparrow\) so absorbed \(\lambda \downarrow\)