Which of the following pairs does not consist of isoelectronic species? (Atomic numbers: $Sm = 62, Er = 68, Yb = 70, Lu = 71, Eu = 63, Tb = 65, Tm = 69$)

• A
  $Sm^{2+}$ and $Er^{3+}$
• B
  $Yb^{2+}$ and $Lu^{3+}$
• C
  $Tb^{2+}$ and $Tm^{4+}$
• D
  Both $(A)$ and $(C)$ are correct