Which of the following have identical bond order? $(i)\; CN^{-} \\ (ii)\;NO_2^{-} \\ (iii)\;NO^{+} \\ (iv)\; CN^{+}$

Question

$(a)\;\text{(i) and (iii) } \\ (b)\;\text{(i) and (iv)} \\(c)\;\text{(ii) and (iv) } \\(d)\;\text{(iii) and (iv)}$