In which of the following electrochemical cell, overall cell reaction is :
` HgO (s) + H_2 (g) rarr Hg E + H_2O(e )`.
A. `Pt | H_2 (g) | H^(+) (aq) |HgO(s) |Hg|Hg€ | Pt`
B. `Pt|H_2(g) |NaOH (aq) |HgO (s) |HgE |Pt`
C. `Pt | H_2(g) |H^(+) ||NaOH(aq)| HgO(s) |Hg € |Pt`
D. ` Pt |H-2 (g) |H^(+) ||HgO(s) |Hg€ |Pt`