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.正确答案AB
