A company changed its policy to have seven-year data retention in the public cloud. Which of the following would be the MOST cost-effective way to meet retention requirements?

Site mirroring maintains a continuous real-time duplicate at a secondary location, doubling storage and bandwidth costs for the entire seven-year period rather than reducing them.

Automated archiving applies lifecycle management policies that tier data from expensive hot storage to significantly cheaper cold or archive storage classes (such as AWS Glacier or Azure Archive Blob Storage) as the data ages, drastically reducing costs over a multi-year retention window. Because the process is automated, it also eliminates operational labor costs associated with manual data management. For a seven-year retention requirement, this approach provides compliance with minimal ongoing spend.

Replication keeps synchronized live copies across regions for high availability, incurring ongoing per-GB storage and egress transfer costs that far exceed the cost of archiving infrequently accessed historical data.

Third-party retention sites introduce additional vendor licensing and service fees on top of storage costs, making them less cost-effective than using native cloud provider archiving capabilities.