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For this question, I thought the correct answer is A, because if we look at the electrode potential, that of iron(III) is higher than that of iodine, therefore the equilibrium for $\ce{Fe^3+}$ will favor the RHS, and shifts to the right, and therefore iodine will go in the opposite direction. Therefore A would be correct.

But the correct answer is D. Using the same logic, I can see it is also correct, but why isn't A correct then?

Thank you for any ideas in advance and sorry for the trivial question.

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The reason is simply semantics. Iodi(n)e which is the neutral valence state of the element will not donate an electron to reduce $\ce{Fe^3+}$ to $\ce{Fe^2+}$. Iodi(d)e which is the anionic form of iodi(n)e has a negative charge and can donate an electron to reduce $\ce{Fe^3+}$ to $\ce{Fe^2+}$.

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