Which of the following alcohols give 2-methylbut-2-ene as the major alkene on heating with conc. $\mathrm{H}{}_2\mathrm{SO}{}_4$ at 443 K?

2-Methylbutan-2-ol gives the tertiary cation directly. 3-Methylbutan-2-ol gives it after a 1,2-hydride shift, and neopentyl alcohol gives it after a 1,2-methyl shift. All three therefore yield 2-methylbut-2-ene (Saytzeff product). Pentan-1-ol has an unbranched skeleton and gives pentenes, not a branched alkene.