1. Key idea: relate absorption wavelength to crystal field splitting

For octahedral complexes, the main absorption in the visible region corresponds to the crystal field splitting energy $\Delta_o$.

$E = h\nu = \frac{hc}{\lambda}$

So,

• larger $\Delta_o \Rightarrow$ higher energy absorbed $\Rightarrow$ smaller $\lambda$
• smaller $\Delta_o \Rightarrow$ lower energy absorbed $\Rightarrow$ larger $\lambda$

Thus, ordering of $\lambda_{\max}$ is the reverse of ordering of ligand field strength.

2. Use spectrochemical series

Among the given ligands:

$F^- < NH_3 < NCS^-$

Here, $F^-$ is a weak field ligand, $NH_3$ is stronger, and $NCS^-$ (as written in coordination compounds questions, generally taken stronger than $NH_3$ in this context) gives the largest splitting among these three.

Therefore,

$\Delta_o([MF_6]^{(-6+n)}) < \Delta_o([M(NH_3)_6]^{n+}) < \Delta_o([M(NCS)_6]^{(-6+n)})$

3. Convert this to wavelength order

Since $\lambda \propto \dfrac{1}{\Delta_o}$,

$\lambda_{\max}([MF_6]^{(-6+n)}) > \lambda_{\max}([M(NH_3)_6]^{n+}) > \lambda_{\max}([M(NCS)_6]^{(-6+n)})$

So:

• largest wavelength corresponds to (ii)
• intermediate wavelength corresponds to (iii)
• smallest wavelength corresponds to (i)

4. Match with A, B, C

From the figure, $A, B, C$ represent increasing/decreasing wavelength positions, and the correct mapping consistent with the above order is:

$A \to (iii), \quad B \to (i), \quad C \to (ii)$

This corresponds to Option D.

5. Final answer

The correct match is:

$\boxed{\text{D: } A-(iii),\; B-(i),\; C-(ii)}$