Hierarchical Storage Management (HSM) is commonly employed in very large data retrieval systems. Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 71.

Hierarchical Storage Management (HSM) provides a continuous on-line backup by using optical or tape “jukeboxes,” similar to WORMs. Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 71.

A Tape Array is a large hardware/software backup system based on the RAID technology.
There is a misconception that RAID can only be used with Disks. All large storage vendor from HP, to EMC, to Compaq have Tape Array based on RAID technology they offer.
This is a VERY common type of storage at an affordable price as well.
So RAID is not exclusively for DISKS. Often time this is referred to as Tape Librairies or simply RAIT. RAIT (redundant array of independent tapes) is similar to RAID, but uses tape drives instead of disk drives. Tape storage is the lowest-cost option for very large amounts of data, but is very slow compared to disk storage. As in RAID 1 striping, in RAIT, data are striped in parallel to multiple tape drives, with or without a redundant parity drive. This provides the high capacity at low cost typical of tape storage, with higher-than-usual tape data transfer rates and optional data integrity.
References: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 70. and Harris, Shon (2012-10-18). CISSP All-in-One Exam Guide, 6th Edition (p. 1271). McGraw-Hill. Kindle Edition.

Digital Audio Tape (DAT) can be used to backup data systems in addition to its original intended audio uses. Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 70.

A Full Backup must be made regardless of whether Differential or Incremental methods are used. Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69. And: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2002, chapter 9: Disaster Recovery and Business continuity (pages 617-619).

The Differential Backup Method is additive because the time and tape space required for each night’s backup grows during the week as it copies the day’s changed files and the previous days’ changed files up to the last full backup. Archive Bits
Unless you’ve done a lot of backups in your time you’ve probably never heard of an Archive Bit. An archive bit is, essentially, a tag that is attached to every file. In actuality, it is a binary digit that is set on or off in the file, but that’s crummy technical jargon that doesn’t really tell us anything. For the sake of our discussion, just think of it as the flag on a mail box. If the flag is up, it means the file has been changed. If it’s down, then the file is unchanged.
Archive bits let the backup software know what needs to be backed up. The differential and incremental backup types rely on the archive bit to direct them. Backup Types
Full or Normal The “Full” or “normal” backup type is the most standard. This is the backup type that you would use if you wanted to backup every file in a given folder or drive. It backs up everything you direct it to regardless of what the archive bit says. It also resets all archive bits (puts the flags down). Most backup software, including the built-in Windows backup software, lets you select down to the individual file that you want backed up. You can also choose to backup things like the “system state”.
Incremental When you schedule an incremental backup, you are in essence instructing the software to only backup files that have been changed, or files that have their flag up. After the incremental backup of that file has occured, that flag will go back down. If you perform a normal backup on Monday, then an incremental backup on Wednesday, the only files that will be backed up are those that have changed since Monday. If on Thursday someone deletes a file by accident, in order to get it back you will have to restore the full backup from Monday, followed by the Incremental backup from Wednesday.
Differential Differential backups are similar to incremental backups in that they only backup files with their archive bit, or flag, up. However, when a differential backup occurs it does not reset those archive bits which means, if the following day, another differential backup occurs, it will back up that file again regardless of whether that file has been changed or not.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69.
And: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2002, chapter 9: Disaster Recovery and Business continuity (pages 617-619). And: http://www.brighthub.com/computing/windows-platform/articles/24531….

One of the key item to understand regarding backup is the archive bit. The archive bit is used to determine what files have been backuped already. The archive bit is set if a file is modified or a new file is created, this indicates to the backup program that it has to be saved on the next backup. When a full backup is performed the archive bit will be cleared indicating that the files were backup. This allows backup programs to do an incremental or differential backup that only backs up the changes to the filesystem since the last time the bit was cleared Full Backup (or Reference Backup) A Full backup will backup all the files and folders on the drive every time you run the full backup. The archive bit is cleared on all files indicating they were all backuped.
Advantages: All files from the selected drives and folders are backed up to one backup set. In the event you need to restore files, they are easily restored from the single backup set.
Disadvantages: A full backup is more time consuming than other backup options. Full backups require more disk, tape, or network drive space.
Incremental Backup An incremental backup provides a backup of files that have changed or are new since the last incremental backup.
For the first incremental backup, all files in the file set are backed up (just as in a full backup). If you use the same file set to perform a incremental backup later, only the files that have changed are backed up. If you use the same file set for a third backup, only the files that have changed since the second backup are backed up, and so on.
Incremental backup will clear the archive bit.
Advantages: Backup time is faster than full backups. Incremental backups require less disk, tape, or network drive space. You can keep several versions of the same files on different backup sets.
Disadvantages: In order to restore all the files, you must have all of the incremental backups available. It may take longer to restore a specific file since you must search more than one backup set to find the latest version of a file.
Differential Backup
A differential backup provides a backup of files that have changed since a full backup was performed. A differential backup typically saves only the files that are different or new since the last full backup. Together, a full backup and a differential backup include all the files on your computer, changed and unchanged.
Differential backup do not clear the archive bits.
Advantages: Differential backups require even less disk, tape, or network drive space than incremental backups. Backup time is faster than full or incremental backups.
Disadvantages: Restoring all your files may take considerably longer since you may have to restore both the last differential and full backup. Restoring an individual file may take longer since you have to locate the file on either the differential or full backup.
For more info see: http://support.microsoft.com/kb/136621 Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69.

Full Backup/Archival Backup -Complete/Full backup of every selected file on the system regardless of whether it has been backup recently.. This is the slowest of the backup methods since it backups all the data. It’s however the fastest for restoring data.
Incremental Backup -Any backup in which only the files that have been modified since last full back up are backed up. The archive attribute should be updated while backing up only modified files, which indicates that the file has been backed up. This is the fastest of the backup methods, but the slowest of the restore methods.
Differential Backup -The backup of all data files that have been modified since the last incremental backup or archival/full backup. Uses the archive bit to determine what files have changed since last incremental backup or full backup. The files grows each day until the next full backup is performed clearing the archive attributes. This enables the user to restore all files changed since the last full backup in one pass. This is a more neutral method of backing up data since it’s not faster nor slower than the other two
Easy Way To Remember each of the backup type properties:
Backup Speed Restore Speed Full 3 1 Differential 2 2 Incremental 1 3
Legend: 1 = Fastest 2 = Faster 3 = Slowest
Source:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69. and http://www.proprofs.com/mwiki/index.php/Full_Backup,_Incremental_%2…

The incremental backup method usually resets the archive bit on the files after they have been backed up.
An Incremental Backup will backup all the files that have changed since the last Full Backup (the first time it is run after a full backup was previously completed) or after an Incremental Backup (for the second backup and subsequent backups) and sets the archive bit to 0. This type of backup take less time during the backup phase but it will take more time to restore.
The other answers are all incorrect choices.
The following backup types also exists: Full Backup -All data are backed up. The archive bit is cleared, which means that it is set to 0. Differential Backup -Backup the files that have been modified since the last Full Backup. The archive bit does not change. Take more time while the backup phase is performed and take less time to restore.
Reference(s) used for this question: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69.

The Full Backup Method is primarily run when time and tape space permits, and is used for the system archive or baselined tape sets. Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69.