Which of the following pair(s) represent(s) the isoelectronic species?

Isoelectronic species are those with the same number of electrons.

${\mathrm{S}}^{2-}$and  ${\mathrm{Sc}}^{3+}=18\text{ electrons ( }16+2\text{ for sulphur, }21-3\text{ for scandium) }$

${\mathrm{SO}}_2$ and ${\mathrm{NO}}_3^{-}=32\text{ electrons }\left(16+16\text{ for }{\mathrm{SO}}_2\text{ and }7+24+1\text{ for }{\mathrm{NO}}_3^{-}\right)$${\mathrm{N}}_2\text{ and }{\mathrm{CN}}^{-}=14\text{ electrons }\left(7+7\text{ for }{\mathrm{N}}_2\text{ and }6+7+1\text{ for }{\mathrm{CN}}^{-}\right)$${\mathrm{NH}}_3\text{ and }{\mathrm{H}}_3{\mathrm{O}}^{+}=10\text{ electrons }\left(7+3\text{ for }{\mathrm{NH}}_3,3+8-1\text{ for }{\mathrm{H}}_3{\mathrm{O}}^{+}\right)$As a result, choices A, B, C, and D are accurate.