The application workload on your database is same between 10 a.m. and 11 a.m. on weekdays. Suddenly you observe poor performance between 10 a.m. and 11 a.m. in the middle of the week. How would you identify the changes in configuration settings， workload profile，and statistics to diagnose the possible causes of the performance degradation？（）

• A、by using the SQL access advisor
• B、by using the Automatic Workload Repository report
• C、by running the Automatic Database Diagnostic Monitor （ADDM）
• D、by using the Automatic Workload Repository Compare Period report
• E、by analyzing the output of the V$ACTIVE_SESSION_HISTORY view