Which one of the following groupings represents a collection of isoelectronic species?

• A
  $Na^{+}, Ca^{2+}, Mg^{2+}$
• B
  $N^{3-}, F^{-}, Na^{+}$
• C
  $Be, Al^{3+}, Cl^{-}$
• D
  $Ca^{2+}, Cs^{+}, Br^{-}$