A precipitate containing $\mathrm{Fe}(\mathrm{OH}){}_3$, $\mathrm{Al}(\mathrm{OH}){}_3$ is treated with excess $\mathrm{NaOH}$ and filtered. The filtrate, on boiling with solid $\mathrm{NH}{}_4\mathrm{Cl}$, gives a white gelatinous precipitate. The species present in the filtrate was

1. A$\mathrm{NH}{}_4[\mathrm{Al}(\mathrm{OH}){}_4]$ only as an undissociated solid
2. B$[\mathrm{Fe}(\mathrm{OH}){}_4]{}^{-}$
3. C$\mathrm{Al}{}^{3+}$
4. D$[\mathrm{Al}(\mathrm{OH}){}_4]{}^{-}$