The alkene shown (a racemic compound; ignore stereochemistry) is treated with (i) $\mathrm{Hg}(\mathrm{OAc}){}_2$, $\mathrm{H}{}_2\mathrm{O}$, then (ii) $\mathrm{NaBH}{}_4$. Which structure is the major product?

The alkene is 3-methylhex-1-ene. Oxymercuration proceeds through a mercurinium ion that water opens at the more substituted carbon (Markovnikov) without any carbocation, so no hydride shift occurs. Demercuration with $\mathrm{NaBH}{}_4$ gives 3-methylhexan-2-ol; acid-catalysed hydration would instead give a rearranged alcohol.