Which backup type backs up the directories, sub-directories, and files that have been manually selected for backing up by an administrator?

A.
Full backup

B.
Selective backup

C.
Incremental backup

D.
Differential backup

Explanation:
A selective backup backs up the directories, sub-directories, and files that have been manually selected for backing up by an administrator.
Incorrect Answers:
A: A full backup backs up all contents of the server, or disk, or drive being backed up.
This includes all directories, sub-directories, and files and data.
C: An incremental backup backs up files that have been added and all data that have been modified since the most recent backup was performed.
D: A differential backup checks each file to determine whether it has been modified or not since the last full backup was performed, and based on this determination, either includes or excludes the file in the differential backup.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 378-380.