Consider the coordination compound,$K_2[Cu(CN)_4]$.A coordinate covalent bond exists between

Question

$\begin{array}{1 1}(a)\;K^+\;and\;CN^-\\(b)\;Cu^{2+}\;and\;CN^{-}\\(c)\;K^+\;and\;[Cu(CN)_4]^{2-}\\(d)\;C\;and\;N\;in\;CN^-\end{array}$