Final answer:
The American citizen's obligation mentioned is attending court when summoned. This duty is a legal requirement as part of maintaining the judicial system. Voting is a critical civic responsibility but not a legal obligation.
Step-by-step explanation:
An example of an American citizen’s obligation, or duty, is B. Attending court when summoned. This is a legal requirement for all U.S. citizens who are eligible jurors. It is a part of civic responsibilities essential to maintain the judicial system and uphold the right to a fair trial. On the other hand, while voting in elections to elect local candidates is an important civic responsibility, and a critical aspect of participating in the democratic process, it is considered a right rather than a legal obligation. Other forms of participation, such as running for public office or understanding how laws are made, are opportunities available to citizens to engage more deeply in the civic life, but they are not mandated duties.
Civic responsibilities such as obeying the law and paying taxes are obligations that apply to all residents, citizens or not, and are foundational to the functioning of society.