In electrolysis of `NaCl` when `Pt` electrode is taken `H_(2)` is liberated at cathode while `Hg` cathode it forms sodium amalgam because
A. Hg is more inert than Pt
B. more voltage is required to reduce `H^(+)` at Hg than at Pt
C. Na is dissolved in Hg while it does not dissolves in Pt
D. concentration of `H^(+)` ions is larger when Pt electrode is taken
