Which reaction below represents the second ionization of sr?

Home Work Help
1

Which reaction below represents the second ionization of sr?

a. sr(g) → sr⁺(g) + e⁻
b. sr2⁺(g) + e⁻ → sr⁺(g)
c. sr⁺(g) + e⁻ → sr(g)
d. sr⁻(g) + e⁻ → sr2⁻(g)
e. sr⁺(g) → sr2⁺(g) + e⁻?