Consider the Following Portion of the Energy-Level Diagram for Hydrogen

Consider the following portion of the energy-level diagram for hydrogen:
-The ionization energy for a hydrogen atom is 1.31 × 10⁶ J/mol. What is the ionization energy for He⁺?

A) 2.18 × 10^-18 J/mol
B) 1.31 × 10⁶ J/mol
C) 5.25 × 10⁶ J/mol
D) 8.72 × 10^-18 J/mol
E) 2.63 × 10⁶ J/mol