A company wants to use Amazon S3 to back up its on-premises file storage solution.

The correct answer isDbecause the company needsNFS supportfor its on-premises environment and wants to back up files intoAmazon S3in themost cost-effectiveway.AWS Storage Gateway File Gatewayis the AWS service designed to present a file interface usingNFS(and SMB) while storing the files as objects in Amazon S3. This allows the company to keep using NFS-based workflows without redesigning the backup process.

The company also wants toarchive the backup files after 5 daysand is willing to waita few daysto retrieve archived data for disaster recovery. That retrieval tolerance aligns well withAmazon S3 Glacier Deep Archive, which is the lowest-cost S3 archival storage class for long-term retention when fast retrieval is not required. By applying anS3 Lifecycle ruleto transition files to Glacier Deep Archive after 5 days, the company can minimize storage cost while still retaining the backups durably in S3.

Option A is incorrect becauseS3 Standard-IAis cheaper than Standard for infrequent access, but it is not archival storage and is more expensive than Glacier Deep Archive for long-term backup retention. Option B is incorrect becauseVolume Gatewayprovides block storage interfaces, not NFS file access. Option C is incorrect becauseTape Gatewayis intended for virtual tape backup workflows, not direct NFS file storage access.

AWS best practices recommendFile Gatewaywhen on-premises applications need file-based access to Amazon S3, andS3 Glacier Deep Archivewhen the lowest-cost archival tier is acceptable. Therefore,File Gateway with a lifecycle transition to S3 Glacier Deep Archiveis the best solution.