What Half-Reaction Occurs at the Cathode During the Electrolysis of Molten

What half-reaction occurs at the cathode during the electrolysis of molten potassium bromide?

A) K(s) → K⁺(l) + e^-
B) Br₂(l) + 2e^- → 2Br^-(l)
C) 2Br^-(l) → Br₂(l) + 2e^-
D) K⁺(l) + e^- → K(s)
E) 2H₂O(l) + 2e^- → H₂(g) + 2OH^-(l)