Explanation:
The alert log will never contain information about external to the database backups, like an operating system backups of the database files.
Incorrect Answers:
1: The alert log shows datafiles in begin backup mode.
2: The alert log shows shutting the database down with an ABORT option.
4: The alert log shows changing the database backup mode from ARCHIVELOG to NOARCHIVELOG. Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 663-666 Chapter 14: Database Failure and Recovery

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