The alcohol shown is heated with concentrated sulfuric acid. Dehydration proceeds through a carbocation that rearranges before proton loss. Which structure shown is the major alkene (most substituted, after rearrangement)?

The alcohol shown is 3,3-dimethylbutan-2-ol. Protonation and loss of water give the secondary 3,3-dimethylbutan-2-yl cation, which undergoes a 1,2-methyl shift to the tertiary 2,3-dimethylbutan-2-yl cation. Loss of the adjacent tertiary C-H proton gives the tetrasubstituted alkene 2,3-dimethylbut-2-ene as the Zaitsev (major) product; the unrearranged alkene and the disubstituted isomer are minor.