Which of the following is a responsibility of a citizen of the United States?

The responsibility of a citizen of the United States encompasses the understanding that breaking laws has consequences. This is a fundamental aspect of civic duty, as it reinforces the idea that laws are in place to maintain order and ensure the rights and safety of all individuals within society. When citizens break laws, they not only affect themselves but also the broader community, thereby upholding the rule of law is essential for a functioning democracy.

While treating others with kindness or joining after-school clubs can be seen as positive social behaviors, they are not formal responsibilities dictated by citizenship. Starting a business is a right enjoyed by citizens but is not a responsibility. The key factor in the correct answer lies in acknowledging the civic duty to adhere to laws and accepting the implications of failing to do so.