Which guideline assesses a person's allegiance to the United States?

The guideline that assesses a person's allegiance to the United States is Guideline A. This guideline focuses on determining an individual's loyalty to the U.S. and evaluating their potential risks to national security based on their connections, activities, or history that may conflict with the interests of the United States. It considers factors that could indicate whether a person is inclined to support or comply with U.S. laws and values, making it fundamental in personnel security assessments.

Each of the other guidelines addresses different areas of concern, such as criminal conduct, financial issues, or personal conduct, and while these factors might indirectly influence someone's allegiance, they do not specifically focus on loyalty as Guideline A does.