Which of the following statements is true regarding implementing a Flashback Table recovery？  （）

• A、 An SCN is never used to perform a Flashback Table recovery.
• B、 If a significant number of changes have been made to the table， row movement must be enabled.
• C、 The tablespace must be offline before performing a Flashback Table recovery.
• D、 Flashback Table recovery is completely dependent on the availability of undo data in the undo  tablespace.