The two core principles underlying fingerprint identification are permanence and which other concept?

• A. Age and gender
• B. Color and thickness
• C. Location and orientation
• D. Permanence and individuality

Answer: (D)

The main idea here is that fingerprint identification rests on two solid observations about fingerprints: they persist over a person’s lifetime, and they are unique to each individual. The permanence part means ridge patterns don’t change much as a person ages, so a print taken years apart can still be matched. The other important idea is individuality—the exact arrangement of ridges and minutiae is so unique that even identical twins have different prints, and the specific pattern in one finger is unlikely to be found in anyone else. This combination—stable patterns over time and unique configurations—allows fingerprints to be used reliably for identification. The other options don’t serve as the foundational basis for identification in the same way: age, color, thickness, or simple location/orientation aren’t the principles guiding why a fingerprint can identify a person.