c
On moving down the group in transition elements, stability of higher oxidation state increases, due to increase in effective nuclear charge.

\( \Rightarrow \mathrm{E}_{\mathrm{Cu}^{+2} / \mathrm{Cu}}^{\circ}=0.34 \mathrm{~V} \)

\( \Rightarrow \mathrm{E}_{\mathrm{H}^{+} / \mathrm{H}_2}^{\circ}=0 \)

\( \mathrm{SRP}: \mathrm{Cu}^{2+}>\mathrm{H}^{+}\)

\(\mathrm{Cu}\) can't liberate hydrogen gas from weak acid.