The correct option is D CH3−CH2−N|CH3−CH3
The boiling point of isomeric amines follow the order 1∘>2∘>3∘. The reason for this can be explained with hydrogen bonding. In primary amines the extent of hydrogen bonding is maximum, so it has the highest boiling point and in tertiary amines, hydrogen bonding is not seen generally, so it has the least boiling point.