In which of the following reactions, increase in the pressure at temperature does not affect the moles at equilibrium:
A. `2NH_(3(g))hArrN_(2(g))+3H_(2(g))`
B. `C_((g))+1//2O_(2(g))hArrCO_((g))`
C. `H_(2(g))+1//2O_(2(g))hArrH_(2)O_((g))`
D. `H_(2(g))+I_(2(g))hArr2HI_((g))`