Which equation best represents the first ionization energy of magnesium?

A.     \({\text{Mg(s)}} \to {\text{M}}{{\text{g}}^ + }{\text{(s)}} + {{\text{e}}^ - }\)

B.     \({\text{Mg(g)}} \to {\text{M}}{{\text{g}}^{2 + }}{\text{(g)}} + {\text{2}}{{\text{e}}^ - }\)

C.     \({\text{Mg(g)}} \to {\text{M}}{{\text{g}}^ + }{\text{(g)}} + {{\text{e}}^ - }\)

D.     \({\text{Mg(s)}} \to {\text{M}}{{\text{g}}^ + }{\text{(g)}} + {{\text{e}}^ - }\)

C