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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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