Which are necessary conditions for the standard hydrogen electrode to have an \({E^\Theta }\) of exactly zero?

I.     Temperature = 298 K

II.     \({\text{[}}{{\text{H}}^ + }{\text{]}} = 1{\text{ mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\)

III.     \({\text{[}}{{\text{H}}_2}{\text{]}} = 1{\text{ mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\)

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

A