You are the network administrator for your company. The network consists of a single Active Directory domain. All network servers run Windows Server 2003. You are directed to back up all files in a folder named C:/Data on one of the servers. You use the Backup utility to perform a normal backup of C:/Data. When the backup is complete, you review the backup log file and discover the following message: "WARNING: Portions of '/Data/Letter.doc' cannot be read. The backed up data is corrupt or incomplete. This file will not restore correctly." You need to ensure that all documents in C:/Data can be restored successfully. What should you do? （）

• A、In the Backup utility, specify an incremental backup. Run the backup again.
• B、In the Backup utility, clear the Disable volume shadow copy option. Run the backup again.
• C、In the attribute properties of C:/Data/Letter.doc, select the File is ready for archiving option. Run the backup again.
• D、In the Offline Settings dialog box of C:/Data, select the All files and programs that users open from the share will be automatically available offline option. Run the backup again.