In the extraction of Al by Hall-Heroult's process, electrolyte contains `Na^+, Ca^(2+)` and `Al^(3+)`. However only Al is discharged at cathode because,

Options

A. `Al^(3+)` ions have higher oxidation potential and discharge potential than `Na^+` and `Ca^(2+)`
B. `Al^(3+)` ions have higher reduction potential and lower discharge potential than `Na^+` and `Ca^(2+)`
C. `Al^(3+)` ions have high reduction potential and discharge potential than `Na^+` and `Ca^(2+)`
D. `Al^(3+)` ions have lower reduction potential and discharge potential than `Na^+`and `Ca^(2+)`