What condition is NOT required to ensure Referential Integrity?

Referential integrity is a key concept in database management that ensures relationships between tables remain valid. In this context, the correct choice highlights a condition that is not a requirement for maintaining referential integrity.

Having multiple foreign keys in a table, at least one join in the related table, and ensuring that referential integrity holds in both directions are all important factors in upholding referential integrity. These conditions help ensure that the relationships between the primary keys in one table and the foreign keys in another are properly respected and consistently maintained.

In contrast, the presence of duplicate records in the linked tables does not inherently violate referential integrity. Referential integrity focuses on the correctness of references between tables, regardless of how many times those references may appear. Therefore, you can still have referential integrity even if duplicate values exist in the foreign key column, as long as those values correctly correspond to a valid primary key in the referenced table. This demonstrates why the condition regarding duplicate records is not required for maintaining referential integrity.