What Are the Two Half Reactions That Show How Many

What are the two half reactions that show how many electrons are gained or lost by each species in the reaction: Ni²⁺(aq) + Mg(s) → Ni(s) + Mg²⁺(aq) ?

A) Ni²⁺(aq) + e^- → Ni(s) and Mg(s) → Mg²⁺(aq) + e^-
B) Ni²⁺(aq) + 2 e^- → Ni(s) and Mg(s) → Mg²⁺(aq) + 2 e^-
C) Ni²⁺(aq) → Ni(s) + 2 e^- and Mg(s) + 2 e^- → Mg²⁺(aq)
D) Ni²⁺(aq) → Ni(s) + e^- and Mg(s) + e^- → Mg²⁺(aq)
E) Ni²⁺(aq) + 2 e^- → Ni(s) and Mg(s) + 2 e^- → Mg²⁺(aq)