The statement(s) that are correct about the species $\mathrm{O}^{2-}, \mathrm{F}^{-}, \mathrm{Na}^{+}$and $\mathrm{Mg}^{2+}$.
(A) All are isoelectronic
(B) All have the same nuclear charge
(C) $\mathrm{O}^{2-}$ has the largest ionic radiil
(D) $\mathrm{Mg}^{2+}$ has the smallest ionic radii
Choose the most appropriate answer from the options given belowi