[不定项选择题]Which two are true about flashback features in Oracle Database 19c and

Later releases? (Choose two.)

A.Flashback logs are automatically purged when
DB_FLASHBACK_RETENTION_TARGET is set lower than the time they have
Already been retained.
B. Flashback logs are monitored and proactively deleted when beyond the
Retention period defined in DB_FLASHBACK_RETENTION_TARGET only after
There is space pressure.
C. Flashback logs are monitored and proactively deleted when beyond the
Retention period defined in DB_FLASHBACK_RETENTION_TARGET before there is
Space pressure.
D. Flashback logs are monitored for being older than the retention period
Defined in DB_FLASHBACK_RETENTION_TARGET and can be deleted by an
Administrator written event trigger.
E. Flashback logs are automatically purged whenever the value of
DB_FLASHBACK_RETENTION_TARGET is changed.