What is one promise you make when you become a United States citizen?

Why this is the answer

The accepted answers put the Oath of Allegiance into plain English. Taking that oath at a naturalization ceremony is the final step to citizenship. Once you have read the oath, the answer list stops feeling like something to memorize. USCIS accepts six promises: give up loyalty to other countries, defend the Constitution and laws of the United States, obey the laws of the United States, serve in the U.S. military if needed, serve the nation by doing important work if needed, and be loyal to the United States. One is enough. The rules behind it rest on Article I of the Constitution, which lets Congress establish a uniform rule of naturalization. Congress used that power to decide how immigrants could become citizens, and several of those requirements still apply, among them living in the United States for a set period, having good moral character, and understanding and supporting the principles of the Constitution. The oath itself is one long sentence. It opens by renouncing every allegiance to a foreign ruler, state or sovereignty you belonged to before, which is where “give up loyalty to other countries” comes from. It continues with a pledge to support and defend the Constitution and laws against every enemy, foreign and domestic, and to bear true faith and allegiance to them, the source of “be loyal.” Three conditional promises follow: to bear arms for the United States, to perform noncombatant service in the Armed Forces, and to do work of national importance under civilian direction, each only when the law requires it. Near its close you declare that you take this obligation freely. One way to miss the question is to offer a good civic habit that the oath never mentions, such as voting or paying taxes. Another is dropping the condition from the service answers. The official wording includes “if needed,” and saying it shows you understand that the promise depends on what the law asks.