In Third Normal Form (3NF), what dependency must be eliminated?

In Third Normal Form (3NF), the main focus is on eliminating transitive dependencies to ensure that all non-key attributes are dependent only on the primary key. This means that every non-key attribute must be fully functionally dependent on the primary key, and there should be no dependencies on any other non-key attributes. This is vital for reducing redundancy and avoiding anomalies when updating the database.

The correct choice emphasizes that all columns in a table should depend solely on the primary key, which is the essence of achieving 3NF. When tables meet this criterion, data integrity improves, and the database design becomes more efficient.

Other options might suggest dependencies that are either irrelevant or not applicable in the context of normal forms. For example, discussing dependencies of non-primary keys on the primary key or dependencies of tables on multiple subjects does not specifically address the need for ensuring that non-key columns derive their values strictly from the primary key, which is foundational to 3NF.