Consider the following complexes \( [\mathrm{CoCl(NH_3)_5}]^{2+} \), \( [\mathrm{Co(CN)_6}]^{3-} \), \( [\mathrm{Co(NH_3)_5(H_2O)}]^{3+} \), \( [\mathrm{Cu(H_2O)_4}]^{2+} \).
The correct order of \( A \), \( B \), \( C \) and \( D \) in terms of wavenumber of light absorbed is: