Which halogen is known to cause the reaction given below :

$$2 \mathrm{Cu}^{2+}+4 \mathrm{X}^{-} \rightarrow \mathrm{Cu}_{2} \mathrm{X}_{2}(\mathrm{s})+\mathrm{X}_{2}$$

<p>The given reaction describes the formation of a copper(II) halide and the corresponding diatomic halogen molecule. Not all halogens will cause this reaction to occur.</p> <p>This reaction is known to occur with iodine (I) because the formation of $\mathrm{I}_{2}$ (a diatomic iodine molecule) is easier due to the relatively low bond energy of the $\mathrm{I}-\mathrm{I}$ bond.</p> <p>On the other hand, the bond energies of $\mathrm{Cl}-\mathrm{Cl}$ and $\mathrm{Br}-\mathrm{Br}$ are higher, making it more difficult for these diatomic halogen molecules to form. Thus, these halogens would not typically cause this reaction to occur.</p> <p>Therefore, the correct answer is:</p> <p>Option B : Only Iodine.</p>