Consider the reaction Upper A u (upper O upper H) subscript 3 plus upper H upper I right arrow upper A U plus upper I subscript 2 plus upper H subscript 2 upper O.. Label the half-reactions as oxidation (use "O") or reduction (use "R"). 2 upper i right arrow upper I subscript 2 plus 2 e superscript minus. Upper A u superscript plus 3, plus 3 e superscript minus right arrow upper A u.
The first loses electrons, so it is Oxidized, and the second one gains electrons, so it is Reduced. (Also I just did this and saw the answers were O and R respectively)