The correct answer to this question is B, By restoring part of the backup. It is recommended to do this process on a quarterly basis, for restoring part of it can help prevent disruptions from corruption to a file. If a person is not regularly restoring their files, it could lead to corruption down the line.
Once a file is corrupted, it is not able to be recovered. It is not necessary to restore everything, but a small number of files can help detect if there are issues that need to be resolved. During recovery, it is also recommended that a check of the hardware is performed.