$Hb{O_2} + {H_3}{O^ + }C{O_2} \rightleftharpoons \left( {{H^ + } - Hb - C{O_2}} \right) + {O_2} + {H_2}O$
Release of $O_2$ is favoured when there is
$\begin{array}{|c|c|c|c|}\hline {} &\text { Molisch's Test} & {\text { Barfoed Test}} & {\text { Biuret Test}} \\ \hline \text { A} & { Positive } & {\text { Negative }} & {\text { Negative }} \\ \hline \text { B } & {\text { Positive }} & {\text { Positive }} & {\text { Negative }} \\ \hline \text { C } & {\text { Negative }} & {\text { Negative }} & {\text { Positive }} \\ \hline\end{array}$
$A, B$ and $C$ are respectively