Which two statements are true about undo segments and the use of undo by transactions in an Oracle database instance? A Undo segments can be stored in the SYSAUX tablespace. B Undo segments can to the first extent when a transaction fills the last extend of the undo segment. C Undo segments can extend when a transaction fills the last extent of the undo segment. D A single transaction may use multiple undo segments simultaneously E Undo segments can be stored in the SYSTEM tablespace. bc