Ahistorian uses the comparative method to
look at similarities and differences across cultures
examine how different cultures formed
determine the meaning of an artifact
record relationships between people and the environment

Generally speaking, a historian uses the comparative method to "look at similarities and differences across cultures," although this can apply to more than analyzing different cultures. 

Idon't think any of em are right, you need to add the number of what paragraph you got your citation from

Protecting and assisting  u.s. citizens  living or traveling abroad; assisting u.s.  businesses  in the international marketplace; coordinating and providing support for international activities of other u.s. agencies (local, state, or federal government), official visits overseas and at home, and other diplomatic efforts.keeping the public informed about u.s. foreign policy and relations with other countries and providing feedback from the public to administration officials.providing  automobile registration  for non-diplomatic staff vehicles and the vehicles of diplomats of foreign countries having  diplomatic immunity  in the united states