Which of these represents the MOST direct way a person could influence the country's foreign policy?

A) voting in a state election
B) donating to a special interest group
C) volunteering for an election campaign
D) writing a letter to one's U.S. Representative

B) donating to a special interest group.

Explanation:

Special interest groups actively seek to influence congressional work and bills through lobbyists, media campaigns but also through financial donations to representatives and senators and their campaigns. This last type of influence is very relevant and is sometimes polemic. You can write a letter to your representative, but it will not have a major impact on his or her congressional work, normally, let´s say. A representative will pay attention to actions by large numbers of people that could affect his or her chances for reelection.