What defines the scope of a differential backup?

• A. It backs up data users specify
• B. It backs up all system files
• C. It includes all data that has changed since the last full backup
• D. It excludes certain database records

Answer: (C)

A differential backup is specifically designed to include all data that has changed since the last full backup. This means that every time a differential backup is performed, it captures all modifications made after the most recent full backup, regardless of previous differential backups. This method is useful for restoring data efficiently; during recovery, you would first restore the last full backup and then apply the latest differential backup to bring the data current.

By contrast, the other options do not accurately reflect the characteristics of a differential backup. While users may specify certain data in other types of backups, differential backups inherently focus on changes from the last full backup. Additionally, backing up all system files describes a full backup, and excluding certain database records is not a standard description for how differential backups function. Thus, the correct choice clearly outlines the primary purpose and scope of a differential backup.