The Acid-Catalyzed Dimerization of Isobutylene Gives a Mixture of Two $\mathrm{B}$

The acid-catalyzed dimerization of isobutylene gives a mixture of two isomeric alkenes (A and $\mathrm{B}$ ) . Hydrogenation of this mixture gives a single $\mathrm{C}_{8} \mathrm{H}_{18}$ hydrocarbon. What is the hydrocarbon?

A) 2,2,4-trimethylpentane
B) 2,3,4-trimethylpentane
C) 2,4-dimethylhexane
D) 2,5-dimethyhexane