Explanation:
A read-only table space needs to be backed up only once after the table space becomes read-only, because no data changes will happen after that to the objects in the table space in read-only mode.
Incorrect Answers:
1: A read-only table space does not need to be backed up at all database backups.
2: You don't need to backup a read-only table space whenever the control file is recreated.
4: It's not necessary to backup a read-only table space when the database is put into ARCHIVELOG mode.
Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 593
Chapter 12: Overview of Backup and Recovery

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