Which of the following archiving methods only backs up data that has changed since the previous fullbackup?

In computer systems, a snapshot is the state of a system at a particular point in time.

An incremental backup is one that provides a backup of files that have changed or are new since the last incremental backup. it is one that backs up only the data that changed since the last backup — be it a full or incremental backup. An incremental backup is a backup of latest changes since the last backup (any level) so that when a full recovery is needed the restoration process would need the last full backup plus all the incremental backups until the point-in-time of the restoration.

Copy backup is a backup that copies all selected files but does not mark each file as having been backed up. In other words, the archive attribute is not cleared.