Which of the following alkenes give 2,3-dimethylbutane on catalytic hydrogenation over Pd/C? Select all that apply.

2,3-Dimethylbutane is $(\mathrm{CH}{}_3){}_2\mathrm{CH}-\mathrm{CH}(\mathrm{CH}{}_3){}_2$. Adding $\mathrm{H}{}_2$ across the C=C of $\mathrm{CH}{}_2=\mathrm{C}(\mathrm{CH}{}_3)-\mathrm{CH}(\mathrm{CH}{}_3){}_2$ or $(\mathrm{CH}{}_3){}_2\mathrm{C}=\mathrm{C}(\mathrm{CH}{}_3){}_2$ gives it. 3,3-Dimethylbut-1-ene gives 2,2-dimethylbutane and 2-methylpent-1-ene gives 2-methylpentane, since hydrogenation does not change the carbon skeleton.