Answer – A
The AWS Documentation mentions the following.
Using cached volumes, you can use Amazon S3 as your primary data storage while retaining frequently accessed data locally in your storage gateway. Cached volumes minimize the need to scale your on-premises storage infrastructure while still providing your applications with low-latency access to their frequently accessed data. You can create storage volumes up to 32 TiB in size and attach them as iSCSI devices from your on-premises application servers. Your gateway stores data that you write to these volumes in Amazon S3 and retains recently read data in your on-premises storage gateway`s cache and upload buffer storage.
Option B is incorrect since this is used for volume storage for EC2 Instances.
Option C is incorrect since this is used for NoSQL storage.
Option D is incorrect since this is used for object storage.
For more information on storage gateway concepts, please refer to the below URL-
https://docs.aws.amazon.com/storagegateway/latest/userguide/StorageGatewayConcepts.html