To meet the requirements of setting up a Scale-Out Backup Repository (SOBR) with immutability for malware protection and specific retention policies, the most fitting configuration is D: Copy and move mode with a Performance Tier configured on a Linux Hardened Repository using the XFS file system and immutability set for 21 days, and a Capacity Tier on Amazon S3 with immutability set for 60 days. This setup utilizes the copy and move mode to ensure that backups are first stored on the on-premises Linux Hardened Repository with an immutability setting that prevents modifications to backups, providing protection against malware for the most recent 21 days of backups. As this on- premises server has limited capacity, older backups beyond 21 days are moved to the Capacity Tier in Amazon S3, where they are also protected with immutability for the entire 60-day retention period. This configuration leverages the strengths of both on-premises and cloud storage while ensuring that all backups are protected from modification or deletion by immutability, aligning with the customer's malware protection concerns and retention requirements.