Amazon S3 is the correct option because EBS snapshots are stored in S3 as incremental point in time backups managed by the EBS service and users do not interact with them as ordinary S3 objects.

The EBS service creates block level, incremental snapshots and writes the snapshot data to Amazon S3 behind the scenes to provide durable and replicated storage. The snapshot lifecycle is managed through the EBS APIs and console so you request restores and copies without directly handling S3 objects.

Amazon EBS is incorrect because snapshots are not kept on EBS volumes themselves. EBS volumes are the live block devices and their snapshots are moved to S3 for durability and efficient incremental storage.

Amazon EFS is incorrect because it is a shared network file system for EC2 and it does not act as the backend for EBS snapshot storage.

EC2 instance store is incorrect because instance store provides ephemeral local host storage and it cannot hold persistent EBS snapshots.

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