3-Bromo-3-methylpentane is heated in ethanol (E1 only). The alkene formed in the greatest amount is

The tertiary cation $\mathrm{CH}{}_3\mathrm{CH}{}_2-\mathrm{C}{}^{+}(\mathrm{CH}{}_3)-\mathrm{CH}{}_2\mathrm{CH}{}_3$ is formed; no shift can improve it. Loss of H from a CH2 gives the trisubstituted 3-methylpent-2-ene; loss from the methyl gives disubstituted 2-ethylbut-1-ene (minor). Between E and Z isomers of 3-methylpent-2-ene the E isomer is more stable, since the two larger groups avoid each other.