3. Acids and Bases

Which of the following best describes the detailed mechanism for a typical polar reaction such as the nucleophilic substitution of $R_{\mathrm{Br}}$ with $\mathrm{OH}-$ to form $R_{\mathrm{OH}}$ and $\mathrm{Br}-$?

Which of the following statements correctly describes the products, including all possible stereoisomers, formed when 2-butene reacts with bromine (${\mathrm{Br}}_2$) in an inert solvent?