You work as a database administrator for Certkiller .com. One of the user sessions was terminated abnormally in the middle of a transaction. What does Oracle database do to recover it？（）

• A、Uses undo data for roll forward
• B、Uses Flashback Log for recovery
• C、Uses online redo logs to roll back
• D、Uses undo data to roll back the transaction
• E、Uses Recovery Manager （RMAN） to roll back
• F、Uses the System Monitor （SMON） background process to perform instance recovery