An organization stores backup files in Cloud Storage. The files will be accessed annually to test the disaster recovery plans. Which storage class is the most cost-effective?

Coldline class is designed for data accessed at most once every 90 days and has a higher per-GB storage price than Archive, making it more expensive for data accessed only annually.

Standard class is optimized for frequently accessed or hot data and carries the highest per-GB storage cost, making it the least economical option for infrequently retrieved backups.

Nearline class targets data accessed at most once per month, with a per-GB storage cost higher than both Coldline and Archive, making it inappropriate and more expensive for annual access.

Cloud Storage Archive class offers the lowest storage cost per GB of any Cloud Storage class and is explicitly designed for data accessed fewer than once per year, such as archival backups and long-term disaster recovery files. Because the backup files in this scenario are only retrieved annually for testing, the low storage cost far outweighs the higher retrieval cost associated with this tier. No minimum storage duration fee for Archive class makes it the clear cost-optimal choice for this access pattern.