Madhuri has configured a backup that will back up all of the changes to a system since the last time that a full backup occurred. What type of backup has she set up?

Differential backups back up all of the changes since the last full backup. An incremental backup backs up all changes since the last incremental backup. A snapshot captures machine state and the full drive at a bitwise level, and full backups are a complete copy of a system but typically do not include the memory state.