Under what circumstance might a US citizen risk losing their citizenship?

A US citizen might risk losing their citizenship in the scenario where they apply for citizenship in another nation. This situation can lead to a presumption of intent to relinquish US nationality, especially if the individual takes an oath of allegiance to the foreign country, which is often a requirement for acquiring citizenship. The U.S. government recognizes that taking such an oath can indicate a voluntary intention to give up your U.S. citizenship, particularly if the circumstances suggest that the individual desires to become a citizen of another country more than to maintain their American citizenship.

While other options suggest varying scenarios regarding dual citizenship and naturalization through marriage, they do not necessarily lead to the automatic loss of U.S. citizenship. For instance, dual citizenship can often be maintained without relinquishing U.S. citizenship, provided the acquisition of the foreign citizenship does not involve any intent or action to give up U.S. nationality. Therefore, the correct option reflects the potential risk associated with applying for citizenship in another nation, signifying a critical aspect of U.S. nationality law.