Referential integrity requires that for any foreign key attribute, the referenced
relation must have:

A.
An attribute with the same value for its secondary key.

B.
A tuple with the same value for its secondary key.

C.
A tuple with the same value for its primary key.

D.
An attribute with the same value for its other foreign key.

Explanation:
The correct answer is “A tuple with the same value for its primary key”. Answers “A tuple with the
same value for its secondary key.” and “An attribute with the same value for its secondary key.”
are incorrect because a secondary key is not a valid term. Answer “An attribute with the same
value for its other foreign key.” is a distracter, because referential integrity has a foreign key
referring to a primary key in
another relation.