You are maintaining a database that is in ARCHIVELOG mode. You have configured the flash recovery area in your database. The database is in MOUNT EXCLUSIVE mode， and you want to configure the Flashback Database feature. Which two options are NOT required to configure the Flashback Database feature？ （）

• A、 Open the database in read-only mode.
• B、 Set the retention target with the DB_FLASHBACK_RETENTION_TARGET initialization parameter.
• C、 Enable the block change tracking feature.
• D、 Execute the ALTER DATABASE FLASHBACK ON statement.