Dehydration of tert-butyl bromide in concentrated acid yields which major alkene?

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Dehydration of a tertiary alkyl halide in concentrated acid proceeds via an E1 mechanism: the leaving group departs to form a very stable tertiary carbocation, then a proton is lost from a β-carbon to give the alkene. The major product follows Zaitsev’s rule—the more substituted double bond is favored. Here the tert-butyl cation has three methyl groups attached as β-carbons, so removing a β-H from any of those methyl groups creates the double bond between the central carbon and a methyl group. That gives 2-methylpropene (isobutene). Because all β-hydrogen eliminations yield the same alkene, it is formed predominantly. The other options aren’t produced by this dehydration: isobutane would be a saturated product, propene would require a different elimination pattern, and tert-butyl alcohol would come from hydration, not dehydration of the halide.