Final answer:
In biometrics, weight is not commonly used as it is not a consistent nor a unique identifier. Instead, fingerprints, voice tones, and retina patterns are favored because they are distinctive and measurable. (option D)
Step-by-step explanation:
The human feature that is generally not used in biometrics is D. Weight. Biometric systems use unique biological traits to identify individuals. Such traits include fingerprints, voice tones, and retina patterns because they are distinctive to each individual and can be measured precisely. Weight, however, does not provide a consistent and unique identifier since it can fluctuate and isn't unique to an individual.
Hence, the answer is option D.