A

\[\ce{Cu_{(s)}}\] ; \[\ce{O_{2(g)}}\]

B

\[\ce{Cu_{(ac}^{2+}}\] ; \[\ce{H2O(\ell)}\]

C

\[\ce{Cu_{(s)}}\] ; \[\ce{H_{2(g)}}\]

D

\[\ce{Cu_{(ac)}^{2+}}\] ; \[\ce{H_{(ac)}^+}\]

E

\[\ce{Cu_{(s)}}\] ; \[\ce{OH_{(ac)}^-}\]