What type of characteristics do biometric systems authenticate?

Biometric systems are designed to authenticate individuals based on unique physical or behavioral traits. These characteristics are inherently tied to the individual and are difficult to replicate or fake, which makes them a very secure method for authentication. Fingerprints are one of the most common biometric traits used in these systems because they provide a high level of uniqueness and are stable over time. Other examples of biometric traits can include facial recognition, iris patterns, or voice recognition.

The other options listed involve systems and identifiers that do not rely on intrinsic human characteristics. Visual patterns like barcodes are typically associated with product identification rather than personal authentication. Digital tokens, such as passwords, are user-created and can be easily stolen or shared, lacking the inherent security of biometric authentication methods. Geographical locations could be used in certain authentication contexts but do not identify individuals uniquely in the same way that physical traits do. Hence, focusing on physical traits such as fingerprints highlights the core functionality of biometric systems, making this the correct answer.