Users notify you that their application is failing every time they try to add new records. Because of
poor application design, the actual ORA error message is unavailable. What might be the problem?(Choose the best answers.)
A. The application user has exceeded their undo quota.
B. The FLASHBACK GUARANTEE option is set on the undo tablespace.
C. The table is currently being queried by a Flashback Transaction Query operation.
D. The table is currently being queried by a Flashback Versions Query operation.
E. The RETENTION GUARANTEE option is set on the undo tablespace.
The likely causes are that the RETENTION GUARANTEE option has been set on the undo tablespace and there are no expired transactions to remove to make room for new transactions,or that the user has exceeded the undo quota that has been set by the database resource manager.
原文：http://www.cnblogs.com/Babylon/p/7826515.html