In case of isoelectronic species the size of F – , Ne and Na + is affected by:

In ${\mathrm{F}}^{-},\mathrm{Ne},{\mathrm{Na}}^{+}$all have $1 {\mathrm{s}}^2,2 {\mathrm{s}}^2,2{\mathrm{p}}^6$configuration. They have different size due to the difference in nuclear charge.

For isoelectronic species, the more nuclear charges, the less will be the size of the species. The valence electrons will experience a greater attractive force due to the increase in nuclear charge.

Hence, the size of isoelectronic species - ${\mathrm{F}}^{-}, \mathrm{Ne}$ and ${\mathrm{Na}}^{+}$ is affected by nuclear charge $\left(\mathrm{Z}\right)$.

Thus, the ionic size of ${\mathrm{Na}}^{+}$ is the lowest, and the ionic size of ${\mathrm{F}}^{-}$ ion is the highest.

Hence, the answer is D.