Which of the following backups is NOT recommended for performing regular backups of an entire system?

A.
Full backup

B.
Incremental backup

C.
Differential backup

D.
Selective backup

Explanation:
Because a selective backup backs up the directories, sub-directories, and files that have been manually selected for backing up by an administrator, it is generally not recommended for regular backups of an entire system. This is due to selective backups being a time-consuming, labor intensive, manual, error-prone process.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 442-443.