What is one responsibility that is required only of United States citizens?

Serving on a jury is a responsibility that is uniquely required of United States citizens. This civic duty is fundamental to the justice system in the U.S., where juries are made up of citizens to ensure that the trial process reflects a cross-section of the community and upholds the principle of a fair trial. The Sixth Amendment of the Constitution guarantees the right to a trial by an impartial jury, and only citizens are eligible to serve on these juries to maintain the integrity and representation within the judicial system.

While paying taxes, voting in elections, and following federal laws are important responsibilities, they are not exclusive to U.S. citizens. Non-citizens, such as lawful permanent residents, are also required to follow federal laws and pay taxes. Voting is a right limited to citizens, but it is not a mandatory responsibility like jury service. Thus, serving on a jury holds a special place as a distinct obligation that reflects civic engagement and participation in democracy, making it the correct answer.