A CloudFormation-managed stack creates EC2 instances. The administrator wants the instances and their data to persist even if someone deletes the CloudFormation stack. Which CloudFormation configuration meets this requirement?

Setting the DeletionPolicy attribute to Retain for the EC2 instance resource in the CloudFormation template ensures that the instance and its associated data volumes are preserved when the CloudFormation stack is deleted. CloudFormation will not terminate the instance, allowing it to continue running independently. Setting DeletionPolicy to Snapshot would create a snapshot of the instance's volumes before deletion, but the instance itself would still be terminated. Using Amazon Data Lifecycle Manager or AWS Backup are valid backup strategies, but they don't directly prevent CloudFormation from deleting the EC2 instance itself when the stack is deleted; they only ensure data recoverability. The core requirement is for the instance and its data to persist, which Retain directly addresses for the instance.