What Must Be Done to the Following Half-Reactions Before They

Multiple Choice

What must be done to the following half-reactions before they can be added together?
Mn (s) → Mn ²⁺(aq) + 2e^-
Fe ³⁺ (aq) + 3 e^- → Fe (s)

A) Double the Mn half-reaction.
B) Double the Mn half-reaction and triple the Fe half-reaction.
C) Triple the Mn half-reaction and double the Fe half-reaction.
D) Add H⁺ ions to the left-side of the Mn reaction.
E) none of the above