To answer this question, you need to understand the different types of backups:
A. Normal backup: This type of backup involves copying all selected files and folders regardless of whether they have been modified since the last backup. It does not consider the previous backups and always creates a full backup. This option does not meet the requirement of backing up only modified files since the last backup and does not minimize the amount of media used.
B. Differential backup: This type of backup involves copying all selected files and folders that have been modified since the last normal backup. It does not consider the previous backups and always creates a backup of the modified files since the last normal backup. While it backs up only modified files, it does not minimize the amount of media used as it includes all modified files since the last normal backup.
C. Incremental backup: This type of backup involves copying only the files that have been modified since the last backup, regardless of whether it was a normal backup or an incremental backup. It uses the least amount of media as it only backs up the modified files. This option meets the requirement of backing up only modified files since the last backup and minimizing the amount of media used.
D. Copy backup: This type of backup involves copying all selected files and folders, similar to a normal backup. However, it does not mark the files as backed up, so subsequent backups may include the same files. It does not meet the requirement of backing up only modified files since the last backup and does not minimize the amount of media used.
The correct answer is C. Incremental backup. This option allows you to perform multiple backups of only those files that are modified since the last backup, while minimizing the amount of media used.