In the Finkelstein reaction $\mathrm{CH}{}_3\mathrm{CH}{}_2\mathrm{Cl}$ is converted into $\mathrm{CH}{}_3\mathrm{CH}{}_2\mathrm{I}$ using $\mathrm{NaI}$ in dry acetone. The reaction goes to completion because

1. A$\mathrm{NaI}$ is insoluble in acetone while $\mathrm{NaCl}$ is soluble
2. B$\mathrm{NaCl}$ is insoluble in dry acetone and precipitates, shifting the equilibrium
3. Cacetone reacts with the $\mathrm{HCl}$ formed
4. D$\mathrm{I}{}^{-}$ is a poorer nucleophile than $\mathrm{Cl}{}^{-}$, so the product cannot revert