C. 2
2H_2O + 2e^(-) → H_2 + 2OH^(-)
2Cl^(-) → Cl_2 + 2e^(-)
2H_2O +Cl^(-) + 2e^(-) → H_2 + Cl_2 + 2OH^(-) + 2e^(-)
2H_2O +2Cl^(-) → H_2 + Cl_2 + 2OH^(-)
This is a redox reaction in which two chloride ions transfer two electrons to two molecules of water.