Which Arrangement Below Orders the Cations from Smallest to Largest

Multiple Choice

Which arrangement below orders the cations from smallest to largest hydration energy? Smallest to largest means least negative hydration energy to most negative hydration energy.

A) Fe^3  Mg^2  Rb^  Na^
B) Na^  Rb^  Mg^2  Fe^3
C) Fe^3  Mg^2  Na^  Rb^
D) Rb^  Na^  Mg^2  Fe^3
E) Na^  Rb^  Fe^3  Mg^2