Answer:
C. Incremental backup
Step-by-step explanation:
An incremental backup is a type of backup where the succeeding copies of the data is made up of only those positions that have changed since the previous or prior copies were made. Such backups are desired since they limit the usage of space for storage and these types of back ups are faster to do that the differential backup.
When we bring this explanation to this question, we can easily see that the backup that is being carried out is done on everything that has changed since the last backup (previous backup). Therefore this is an incremental backup.