Which of the following represents a sheet (two-dimensional) silicate anion?

In a sheet silicate each $\mathrm{SiO}{}_4$ tetrahedron shares three of its oxygens, giving the unit $\mathrm{Si}{}_2\mathrm{O}{}_5{}^{2-}$ per Si (formula $(\mathrm{Si}{}_2\mathrm{O}{}_5){}_n{}^{2n-}$). $(\mathrm{SiO}{}_3){}_n{}^{2n-}$ is a chain or ring, $\mathrm{Si}{}_2\mathrm{O}{}_7{}^{6-}$ is a pyrosilicate and $\mathrm{SiO}{}_4{}^{4-}$ is an orthosilicate.