If crystal field theory is completely followed, then which of the following statements must' be true?

Anionic ligands such as${\mathrm{OH}}^{-}$ should exert greater splitting effect than neutral ligands such as ${\mathrm{H}}_2\mathrm{O}$

Colour of complexes cannot be explained

Complexes will have partial covalent bonds between ligands and central atom

Complexes will have pure covalent bonds between ligands and central atom