Final answer:
One responsibility exclusively for United States citizens is to serve on a jury and vote in a national election.
Step-by-step explanation:
One responsibility that is only for United States citizens is to serve on a jury and vote in a national election. These responsibilities are exclusive to citizens because they are considered fundamental to the democratic process and the functioning of the justice system. Being a juror ensures that fair trials are conducted, while voting allows citizens to participate in the decision-making process of their government.
Learn more about Responsibility for United States citizens