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Why are keys NOT decided by inspecting the data alone?

Athe data is encrypted and unreadable
Bindexes can be built only by hand
Cdata may look unique by chance; only meaning decides
Dkeys are forbidden on attributes with NULLs
Answer & Solution
Correct answer: C. data may look unique by chance; only meaning decides
**NPTEL is explicit:** 'Keys can be determined only from the meaning of the attributes in the entity type. Determined by the designers.' Distinct values today don't imply uniqueness forever only the designer's domain understanding does.
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