A global ecommerce company needs scalable storage for legacy on-premises file-based applications. Requirements: be able to mount volumes as iSCSI devices from on-prem application servers, keep low-latency access to frequently accessed data, and take point-in-time copies of volumes using AWS Backup. Which solution satisfies these requirements?

The correct solution is to provision an AWS Storage Gateway volume gateway in cache mode. This directly addresses the requirement for iSCSI block storage, allowing on-premises applications to mount volumes as iSCSI devices. Cache mode ensures low-latency access to frequently accessed data by storing it locally while asynchronously uploading all data to Amazon S3. AWS Backup can then be used to take point-in-time copies of these Storage Gateway volumes. An AWS Storage Gateway tape gateway is incorrect because it emulates a virtual tape library and is not designed for iSCSI block storage for file-based applications. Provisioning both an Amazon FSx File Gateway and an Amazon S3 File Gateway is incorrect because neither provides iSCSI block storage directly for legacy applications; they are file gateways. An AWS Storage Gateway file gateway in cache mode is incorrect because it provides NFS and SMB file protocols, not iSCSI block storage.