A . REDO is used for read consistency.False. Read consistency is achieved using UNDO, which provides a consistent view of data as of a specific point in time. REDO logs changes for recovery, not consistency.
B . UNDO is used for some flashback operations.True. Flashback features like Flashback Query and Flashback Table rely on UNDO to reconstruct past states of data.
C . UNDO is used for read consistency.True. UNDO stores pre-change data, enabling multi-version read consistency for queries.
D . Both REDO and UNDO can be multiplexed.False. REDO logs can be multiplexed (mirrored across multiple destinations), but UNDO is managed within a single UNDO tablespace per instance (though it can have multiple data files).
E . REDO is used for ROLLBACK.False. ROLLBACK uses UNDO to revert changes; REDO logs the changes but isn't used to undo them.
F . REDO is used for instance recovery.True. REDO logs are replayed during instance recovery to reapply committed changes after a crash.