What characteristic does biometrics use for identification?

Biometrics relies on unique human physical characteristics for identification and authentication purposes. This can include various traits such as fingerprints, facial recognition, iris patterns, and voice recognition, among others. Each of these characteristics is inherent to the individual and difficult to replicate or forge, making biometrics a highly effective method for ensuring secure access to systems and sensitive information.

The focus on human physical traits allows biometric systems to establish identity based on something that is both unique to an individual and tied to their biological makeup. This method enhances security measures, as it relies on information that is generally stable over time and that cannot be easily lost or forgotten, unlike passwords or PINs.

In contrast, the other choices do not pertain to the core concept of biometrics. Classified information is related to data security classifications, geographical data pertains to location-based services, and network signatures involve patterns related to data packets in computer networks. None of these are based on inherent human physical traits, which is fundamental to biometric identification.