Sodium metal can be extracted by either Castner's Process or Down's process
Castner's process.
Electrolyte `to` fused `NaOH`
Cathode and anode are made up of a steel rod and `Ni` cylinder respectively the reaction takes place as follows :
At cathode `Na^(+)+e^(-)toNa`
At anode `OH^(-)to(1)/(2)H_(2)O+(1)/(4)O_(2)uarr+e^(-)`
Down's process :
Electrolyte `to` fused `NaCl` and `CaCl_(2)`
Cathode and anode are ring shaped iron metal and graphite respectively. The reaction takes place as follows :
`Na^(+)+e^(-)toNa`
`Cl^(-)to(1)/(2)Cl_(2)uarr+e^(-)`
`CaCl_(2)` is used along with `NaCl` due to

Options

A. Increase in electrical conductivity of `NaCl`
B. Lowering in melting point of the mixture compared to pure `NaCl`
C. `CaCl_(2)` protects `Na` from getting vapourized
D. Visocosity of the mixture of `NaCl` or `CaCl_(2)` is lower than pure `NaCl`.