The number of files Susan needs to restore is three because she has full backup and the three files have crashed.
The most recent, previous complete data backup is used to create a differential backup. Only the data that has changed since the last full backup is captured in a differential backup. The basis of the differential is the full backup that a differential backup is based on.
Susan performs a full backup of her server every Sunday at 1:00 a.m. and differential backups on Mondays through Fridays at 1:00 a.m.
The server crashed on Wednesday at 9:00 am.
Since the Susan has full backup of her data which she did on Sunday at 1:00 am
Differential backups on Monday through Fridays at 1:00 a.m
So the number of files Susan needs to back up is three because the backup file which is taken on Wednesday at 1:00 am has also failed.
Thus, the number of files Susan needs to restore is three because she has full backup and the three files have crashed.
Learn more about the differential backup here:
https://brainly.com/question/14017082
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