Which of the following is correct for ${\mathrm{CsBr}}_3$

It contains ${\mathrm{Cs}}^{+} \mathrm{and} {{\mathrm{Br}}_3}^{-}$ ions

It is a covalent compound

It contains ${\mathrm{Cs}}^{+}, {\mathrm{Br}}^{-}$ and in lattice ${\mathrm{Br}}_2$ molecules

It contains ${\mathrm{Cs}}^{3+} \mathrm{and} {\mathrm{Br}}^{-}$ ions