What Are the Two Half Reactions That Show How Many $\rarr$

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) $\rarr$ Ni(s) + Mg²⁺(aq) ?

A) Ni²⁺(aq) + e^- $\rarr$ Ni(s) and Mg(s) $\rarr$ Mg²⁺(aq) + e^-

B) Ni²⁺(aq) + 2 e^- $\rarr$ Ni(s) and Mg(s) $\rarr$ Mg²⁺(aq) + 2 e^-

C) Ni²⁺(aq) $\rarr$ Ni(s) + 2 e^- and Mg(s) + 2 e^- $\rarr$ Mg²⁺(aq)

D) Ni²⁺(aq) $\rarr$ Ni(s) + e^- and Mg(s) + e^- $\rarr$ Mg²⁺(aq)

E) Ni²⁺(aq) + 2 e^- $\rarr$ Ni(s) and Mg(s) + 2 e^- $\rarr$ Mg²⁺(aq)