A company runs Multi-AZ Amazon RDS for PostgreSQL for customer portal backends. The company needs to implement a 30-day backup retention policy. The company currently has both automated RDS backups and manual RDS snapshots and wants to keep both types of existing backups that are less than 30 days old. Which solution meets these requirements MOST cost-effectively?

The most cost-effective solution is to configure the RDS automated backup retention to 30 days and manually delete older manual snapshots. RDS automated backups are managed by AWS and automatically deleted after their retention period, providing a cost-effective way to manage their lifecycle. Manual snapshots, however, persist indefinitely until manually deleted. Therefore, to meet the 30-day retention for manual snapshots, they must be manually removed. AWS Backup is not strictly necessary for this specific requirement and adds complexity. Disabling automated backups would remove a key recovery mechanism and is not recommended. Using CloudFormation for deletion is an automation method but doesn't change the fundamental need to manage manual snapshots separately from automated backups, and manual deletion is simpler for this specific scenario.