Which of the following is NOT one of the responsibilities of U.S. citizens?

U.S. citizens have specific responsibilities that are mandated by law, such as registering for the draft, voting in elections, and paying taxes. These actions are crucial to the functioning of democracy and the role of citizens in supporting their government and society.

Traveling abroad, however, is not considered a responsibility of citizenship. While it is a right and a privilege available to citizens, it does not carry the same legal obligations or societal expectations that the other options do. Citizens are encouraged to participate in civic duties like voting and paying taxes, but choosing to travel is a personal decision that does not directly impact their responsibilities as a citizen. Thus, traveling abroad is the correct choice as it does not fit within the defined responsibilities of U.S. citizens.