The reaction below was carried out in an acidic solution.

Upper I minus, plus upper I upper O minus subscript 3 right arrow upper I subscript 2.

Which statement is true about this equation?
Although it is unbalanced, it can be balanced by using the half-reaction method.
It has been balanced by using the half-reaction method.
It has been balanced by directly using spectator ions.
Although it is unbalanced, it can be balanced by directly using spectator ions.