$\mathrm{Cu}^{2+}$ does not form $\mathrm{CuI}_2$. This is because $\mathrm{Cu}^{2+}$

• A

  reduces $\mathrm{I}^{-}$to $\mathrm{I}^{3-}$
• B

  undergoes self oxidation and reduction to form $\mathrm{Cu}$ and $\mathrm{Cu}^{3+}$
• Correct answer
  C

  oxidizes $\mathrm{I}^{-}$to $\mathrm{I}_2$
• D

  is unstable in water

Hence, the correct answer is option: 'C'.