The most stable ion is

Options

1. A$\left[\mathrm{Fe}(\mathrm{OH})_{3}\right]^{3-}$
2. B$\left[\mathrm{FeCl}_{6}\right]^{3-}$
3. C$\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}$
4. D\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}