What is the order of increasing boiling point for the isomers of C5H12: CH3CH2CH2CH2CH3, CH3CH(CH3)CH2CH3?

a) CH3CH2CH2CH2CH3 < CH3CH(CH3)CH2CH3
b) CH3CH(CH3)CH2CH3 < CH3CH2CH2CH2CH3
c) They have the same boiling point.
d) It cannot be determined.