Oxidation number of iodide in IO ,IO ,KI and I respectively, are

Let us consider the oxidation states of iodine for each given compound as x. As we know, 2I is in elemental state 3 4 2 IO x 6 1 x 5 IO x 8 1, x 7 KI 1 x 0, x 1 I x 0 → → → → Therefore, C is the right option.