Ferric sulphate on heating gives sulphur trioxide . The ratio between the weights of oxygen and sulphur present in $SO_3$ obtained by heating 1 kg of ferric sulphate is $(Fe_2(SO_4)_3 \to Fe_2O_2+SO_3)$

Question

$\begin{array}{1 1} (a) \;2:3 \\ (b) \;1:3\\ (c) \;3:1\\ (d) \;3:2\end{array} $