The alcohol shown is heated with concentrated $\mathrm{H}{}_2\mathrm{SO}{}_4$ and the major alkene is isolated. Which structure is the major alkene, allowing for rearrangement of the intermediate carbocation?

The alcohol is 3-methylbutan-2-ol. Loss of water gives a secondary cation, and a hydride shift from the adjacent tertiary carbon gives the more stable tertiary cation. Saytzeff elimination from this cation gives 2-methylbut-2-ene as the major product, while 3-methylbut-1-ene would be the unrearranged product.