Boiling point of alkanes increases with molecular mass and surface area available for van der Waals interactions. n-Pentane (C₅H₁₂, bp 36 °C) has the highest molecular mass among the options AND is unbranched, maximising the contact surface area for London dispersion forces. n-Butane and isobutane are both C₄ isomers with lower molecular mass. Neopentane is a C₅ isomer but its highly compact spherical shape minimises surface contact, giving it the lowest bp (9.5 °C) among C₅ isomers. Therefore n-Pentane has the highest boiling point of the given choices.