Which of the following ligands has the highest field strength?

The correct increasing order for the wavelengths of absorption in the visible region for the complexes of $Co^{3+}$ is:

Which ligand among the following has the highest splitting power of $d$-orbitals of the central metal ion?

Among the following species,the one which causes the highest $CFSE, \Delta _0$ as a ligand is

The complex with the highest magnitude of crystal field splitting energy $\left(\Delta_0\right)$ is

The correct statements among $I$ to $III$ are:
$I$. Valence bond theory cannot explain the color exhibited by transition metal complexes.
$II$. Valence bond theory can predict quantitatively the magnetic properties of transition metal complexes.
$III$. Valence bond theory cannot distinguish ligands as weak and strong field ones.