Which components are used to make the standard hydrogen electrode?

A.     \({{\text{H}}_{\text{2}}}{\text{(g), }}{{\text{H}}^ + }{\text{(aq), Pt(s)}}\)

B.     \({{\text{H}}_{\text{2}}}{\text{(g), }}{{\text{H}}^ + }{\text{(aq), Ni(s)}}\)

C.     \({{\text{H}}_{\text{2}}}{\text{(g), H}}{{\text{O}}^ - }{\text{(aq), Pt(s)}}\)

D.     \({{\text{H}}_{\text{2}}}{\text{(g), H}}{{\text{O}}^ - }{\text{(aq), Ni(s)}}\)

A