Your boss at Supportcenter.cn wants you to clarify Oracle 10g. Which statement regarding the usage of redo log files during instance recovery is true？ （）

• A、Transactions are rolled back using redo log files.
• B、Transactions are rolled forward using redo log files.
• C、Transactions are rolled back using redo log files and archived log files.
• D、Transactions are rolled forward using redo log files and rolled back using redo log files.