The correct option is D All of the above are correct
The redox reaction is shown below:
Cr(OH)3+(OH)−+IO3−→CrO42−+H2O+I−
The oxidation number of I changes from +5 to −1.
Thus, each iodine takes 6 electrons and is reduced.
Hence, IO3− is the oxidizing agent.
The oxidation number of chromium changes from +3 to +6.
Thus, Cr(OH)3 is oxidized.