Among the following substituted silanes the one which will give rise to cross linked silicone polymer on hydrolysis is

${\text{SiCl}}_4+{\mathrm{R}}^{-}{\mathrm{Mg}}^{+}\mathrm{X}\to \underset{ \mathrm{Alkyltrihydroxysilane} }{{\mathrm{RSiCl}}_3}+\mathrm{Mg}\left(\mathrm{X}\right)\mathrm{Cl}$

                 Cross linked silicones

RSiCl₃ on hydrolysis gives   Cross linked silicones