The correct option is B n-hexane
Boiling point in alkane depends upon the chains of atoms and the molecular mass of the molecules. Straight-chain molecules have higher boiling point than the branched-chain compounds.
Higher molecular mass molecules have higher boiling point than the lower mass molecules.
Among given compound 2, n-hexane is a straight chain molecule and higher molecular mass thus it has the highest boiling point. Further, the boiling point of these compounds follows the order : n-hexane >n-pentane > 2-methylbutane > 2, 2-dimethylpropane.