Which of the following is a responsibility of U.S. citizens?

The correct answer is that all of the choices represent responsibilities of U.S. citizens. Voting is a fundamental way through which citizens participate in the democratic process, influencing government decisions and policies through their electoral choices. Paying taxes is also a crucial responsibility as it provides the government with the necessary funds to operate effectively, which supports public services and infrastructure essential for society's functioning. Serving on juries is another vital civic duty, as it ensures that citizens participate in the judicial process, upholding the legal system and contributing to fair trials.

Each of these responsibilities reflects the active role that citizens must play in maintaining a functioning democracy. By fulfilling these duties, citizens contribute to the overall health and stability of the government and the society in which they live.