Question

each fingerprint is unique because of:
a biometrics
b powder
c ridges in the skin
d oils in the skin

Explanation:

Fingerprints are unique due to the distinct pattern of ridges on the skin. Biometrics is a general field (not the cause). Powder is used for fingerprint detection, not the reason for uniqueness. Oils help in leaving prints but don't make them unique.

Answer:

C. Ridges in the skin