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The primary key is selected from the:

  • A.composite keys.
  • B.determinants.
  • C.candidate keys.
  • D.foreign keys.

Answer: C

Correct answer: candidate keys.

A candidate key is any minimal set of attributes that uniquely identifies a row, and a relation may have several. The designer selects one of them as the primary key; the rest remain candidate keys and are usually given unique constraints. Foreign keys reference a key in another relation, and determinants need not be unique at all.

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