The correct option is Hands face and eyes.

Hands face and eyes are most readily available because they cover widely used physiological traits such as fingerprints and hand geometry, facial features, and the eye structures used in iris or retina recognition. These traits are relatively easy to capture with standard sensors, they offer high distinctiveness and permanence, and they are supported by mature standards and large deployments which makes them the default choices in practical systems.

Feet and hair are not commonly used for general biometric recognition because hair style and coverage change frequently and hair is not inherently unique in the way fingerprints or irises are. Feet are also impractical for routine identification because capturing foot features reliably is difficult in most operational settings.

Voice and gait are behavioral biometrics and they can vary with health, emotion, background noise, footwear and environment. They are useful in some scenarios but they are less stable and less discriminating than fingerprints or iris scans which makes them less common as primary identifiers in many systems.

Neck and mouth are not standard biometric modalities for identity systems. These areas are often occluded by clothing or accessories and there are few established sensors and standards for reliable recognition of the neck or mouth alone which limits their practicality.

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