A CloudFormation template provisions an Amazon RDS instance to create disposable development environments; the stack is deleted when the environment is no longer needed. The RDS data must persist beyond stack deletion so it can be reused. What is the most reliable and efficient method to ensure the RDS data is retained after the stack is deleted?

The most reliable and efficient method is to set the DeletionPolicy attribute to Snapshot for the RDS instance resource in the CloudFormation template. This ensures that a final DB snapshot is created and retained when the stack is deleted, allowing the data to persist independently of the stack. Option 1 is inefficient and unnecessary; continuous backups every five minutes are excessive for this use case and don't directly address persistence upon stack deletion. Option 2 requires manual intervention, which is prone to error and not automated. Option 4 is overly complex; creating a separate CloudFormation template just for backup is less efficient than using the built-in DeletionPolicy attribute.