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 typically involves keeping exact copies of data in sync across multiple locations for high availability and disaster recovery, which is more expensive than long-term archiving due to continuous synchronization and higher storage tiers.

Automated archiving involves moving infrequently accessed data to lower-cost, long-term storage tiers, such as cold storage or archive storage classes offered by cloud providers. This method is highly cost-effective for long-term retention requirements because these storage tiers are designed for durability and infrequent access at a significantly lower per-GB cost compared to active or hot storage.

Replication involves creating multiple copies of data for redundancy and availability, often in active storage tiers, making it more expensive for long-term, infrequently accessed retention than dedicated archive solutions.

Using "third-party sites" is too vague; while a third-party service might offer archiving, the term itself doesn't specify a cost-effective method and could refer to various expensive solutions like active data centers.