Explanation:
ARCHIVE LOG mode is essential for backup of production database. Open database backups will be required for a 24 hours a day, 7 days a week production environment. Incorrect Answer:
2: NO ARCHIVE LOG mode of the database cannot provide 24 hours a day, 7 days a week database availability: it requires to shutdown database for backup.
4: Consistent whole backups can be considered as correct answer, but open database backup is more correct and full answer.
Reference:
OCP Oracle 9i Database: Fundamentals II Exam Guide, Rama Velpuri, p. 187-189
Chapter 8: Configuring the Database Archive Mode

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