Answer: A, B, C
In the first reaction I (+5) and I (-1) converge on I (0), which is comproportionation, and the mole ratio IOX3X− : IX2 is 1 : 3, so 0.10 mol gives 0.30 mol. In the second, S goes from +4 to 0, a gain of 4 electrons per SOX2. The S of HX2S goes from -2 to 0, so it is oxidised, not reduced.