Explanation:
Incremental backups are non-cumulative by default, each file in a backup set must have the same block size, a control file backup set cannot contain any other types of files.
Incorrect Answers:
4: With multilevel incremental backups, you can have a level 0-4 backups, in which only the block changed since the last full backup will be taken. There must be an associated level-0 backup for the database with AVAILABLE status in the recovery catalog in order to define the baseline for the incremental.
5: In a full backup, recover manager will save every block in a datafile (except for datafile blocks that have never been used), while an incremental level-0 backup will skip empty blocks.
Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 585-591
Chapter 12: Overview of Backup and Recovery

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