Final answer:
Voting in federal elections is a responsibility that is exclusive to U.S. citizens.
Step-by-step explanation:
One responsibility that is only for U.S citizens, and is considered a civic must do, is voting in federal elections. Citizens have the unique right and responsibility to elect representatives and leaders that will partake in shaping the nation’s policies and laws. It's a fundamental aspect of American democracy and an important way for citizens to express their voices. By participating in elections, U.S. citizens ensure that government actions reflect the interests and concerns of the majority. To maintain a representative democracy where elected officials are truly reflective of the populace's desires, it's crucial that every eligible citizen registers and participates in the voting process.