The best combination for cost efficiency and durability is Configure EBS snapshot lifecycle policies for automated creation and time based retention and Rely on incremental EBS snapshots so only changed blocks are saved. Lifecycle policies automate creation, retention, and deletion to control snapshot sprawl, while EBS snapshots are inherently incremental so you only pay for changed blocks. Use S3 Lifecycle rules to transition EBS snapshots to S3 Glacier Deep Archive is invalid because EBS snapshots are not S3 objects and cannot be transitioned using S3 Lifecycle, even though an EBS snapshot archive tier exists and is managed via EBS APIs, not S3. Enable EBS Multi-Attach on volumes to improve durability does not provide backups or extra durability. It enables concurrent access for certain io volume types and does not reduce storage costs. Copy snapshots to a separate AWS account to enhance resilience can improve isolation or governance but duplicates data and increases storage cost, which conflicts with the cost-minimization goal. Remember that EBS snapshots are incremental by default and that Data Lifecycle Manager automates retention and deletion. Be wary of distractors that involve S3 Lifecycle for snapshots or features like Multi-Attach that do not address backup cost or durability.