What does the rollback operation do in a database transaction?

The rollback operation serves a critical function in database transactions by allowing the system to revert to a previous state in case of an error or failure during the transaction process. Specifically, when a transaction is underway and an issue arises—such as a violation of constraints, a system crash, or manual interruption—the rollback command ensures that any changes made during that transaction are undone, effectively restoring the database to its last committed state. This is essential for maintaining data integrity and ensuring that the database remains consistent, particularly in environments with concurrent transactions.

In contrast to the other options, which suggest actions like deleting tables, permanently saving changes, or transferring data, rollback focuses solely on reversing changes from incomplete transactions. This helps prevent partial updates to the database that could lead to inconsistencies or corruption in the data stored.