Which of the following are isoelectronic and isostructural ? $NO_3^{-},CO_3^{2-},ClO_3^{-}, SO_3$

Question

$(a)\;NO_3^{-},CO_3^{2-} \\ (b)\;SO_3,NO_3^{-} \\(c)\;ClO^{-}_3 \\(d)\;CO_3^{2-},SO_3 $