What should a solutions architect recommend that is MOST cost-effective?

Explanations:

Enabling object-level versioning and S3 Object Lock in governance mode allows for versioning and the ability to delete or modify objects based on the governance rules. However, it does not prevent all changes to the data, which means compliance with the requirement to preserve all previous states of the object may not be guaranteed.

While enabling object-level versioning and S3 Object Lock in compliance mode ensures that no object versions can be deleted or altered for a specified retention period, it does not address the cost-effective archiving of objects older than 5 years, which is essential for the scenario described.

This option meets the compliance requirement of preserving previous states of objects through versioning. Additionally, implementing a lifecycle policy to move objects older than 5 years to S3 Glacier Deep Archive effectively archives the data at a lower cost, satisfying the requirement for auditing while minimizing storage expenses.

Enabling object-level versioning and using a lifecycle policy to move data older than 5 years to S3 Standard-IA does not provide sufficient archiving. S3 Standard-IA is not as cost-effective for long-term storage as S3 Glacier Deep Archive, and the requirement specifies that the data must be archived for auditing.