Isoelectronic species are those that have the same number of electrons. Isostructural species have the same geometric arrangement of atoms.

First, let's determine if the given pairs are isoelectronic.

• $$NO_3^-$$: Nitrogen has 7 electrons, and each oxygen has 8 electrons. The negative charge adds one more electron. Therefore, $$NO_3^-$$ has $$7 + 3 \cdot 8 + 1 = 32$$ electrons.
• $$CO_3^{2-}$$: Carbon has 6 electrons, each oxygen has 8 electrons, and the $${2-}$$ charge adds 2 more electrons. Therefore, $$CO_3^{2-}$$ has $$6 + 3 \cdot 8 + 2 = 32$$ electrons.
• $$ClO_3^-$$: Chlorine has 17 electrons, each oxygen has 8 electrons, and the negative charge adds 1 more electron. Therefore, $$ClO_3^-$$ has $$17 + 3 \cdot 8 + 1 = 42$$ electrons.
• $$SO_3$$: Sulfur has 16 electrons, and each oxygen has 8 electrons. Therefore, $$SO_3$$ has $$16 + 3 \cdot 8 = 40$$ electrons.

Based on the number of electrons, $$NO_3^-$$ and $$CO_3^{2-}$$ are isoelectronic.

Now, let's determine if these species are isostructural. Both $$NO_3^-$$ and $$CO_3^{2-}$$ have a trigonal planar structure.

Therefore, the correct option is:

Option A: $$NO_3^-$$, $$CO_3^{2-}$$