Explanation:
You need to restore just damaged files to minimize data log if no log switch has occurred once the last backup. When media failure occurs on the database in NOARCHIVELOG mode, you must restore all datafiles, redo log files, and control files from your backup in order to recover the database, even if only one file on disk was lost. This is because all datafiles, redo logs, and control files must be synchronized in order for the database to open. One exception to this rule is when your database experiences media failure and no online redo log has been overwritten by LGWR. In this case, you need only restore the datafile lost by media failure and let Oracle handle crash recovery.
Incorrect Answers:
1: You can restore only damaged files if no log switch has occurred once the last backup. In other case, when LGWR rewrote redo logs, you need to restore all datafiles, redo logs, and control files.
3: Not only consistent datafiles need to be restored, but redo logs, and control files also.
4: Not only datafiles need to be restored, but redo logs, and control files also.
Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 666-671
Chapter 14: Database Failure and Recovery

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