Which of the following alkenes give a rearranged alkyl bromide as the major product with $\mathrm{HBr}$ in the absence of peroxide?

3-Methylbut-1-ene gives a secondary cation that undergoes a hydride shift to a tertiary cation. 3,3-Dimethylbut-1-ene undergoes a methyl shift. 2-Methylbut-2-ene gives a tertiary cation directly and propene gives a secondary cation that cannot improve, so neither rearranges.