The gas evolved on heating $\;CaF_{2}\;$ and $\;SiO_{2}\;$ with concentrated $\;H_{2}SO_{4}\;$ ,on hydrolysis gives a white gelatinous precipitate . The precipitate is :

Question

(a) hydrofluosilicic acid\[\](b) silica gel\[\](c) silicic acid \[\](d) calciumfluorosilicate