Which Statement Best Describes Why Amine I Has a Lower

Which statement best describes why amine I has a lower boiling point than II and III?

A) I has a lower molecular weight.
B) I does not have a hydrogen attached to the nitrogen and so it does not form a hydrogen bond.
C) I is more highly branched and so it does not form as many dipole-dipole interactions between the carbon and nitrogen.
D) I has a higher molecular weight.
E) I cannot form an ion.