Answer:
- 1 is the correct option
Explanation:
In determining the oxidation state or formal charge on element in an ionic specie, the whole ion need to be equated to the value of charge on the ion.
For example in this case, the charge on the ion is -3. Thus; representing iodine with X and putting -2 for the oxidation state of O (oxygen)
X + -2 = -3 (adding 2 to both side)
X = -3 + 2
X = - 1