# A mixture of $Al(OH)_3$ and $Fe(OH)_3$ can be separated by

$\begin{array}{1 1}(a)\;HCL&(b)\;NH_4OH\\(c)\;NaOH&(d)\;HNO_3\end{array}$

Excess of NaOH with aluminium hydroxide dissolves white ppt.Where as ppt of ferric hydroxide does not dissolve with NaOH.
Hence (c) is the correct answer.