You work as a database administrator for Certkiller .com. Users complain that their query is taking a long time to complete. You suspect the database buffer cache size to be the reason， and you define an alert to be generated when the buffer cache hit metric goes below 85%. When you observe the dynamic performance views， you find that the buffer cache hit ratio is 81% but no alerts are being generated.  What could be the reason for this problem？（）

• A、The advisory memory has been turned off.
• B、The DB_CACHE_ADVICE parameter has been set to OFF in the parameter file.
• C、The STATISTICS_LEVEL parameter has been set to BASIC in the parameter file.
• D、The TIMED_STATISTICS parameter has been set to FALSE in the parameter file.
• E、The STATISTICS_LEVEL parameter has been set to TYPICAL in the parameter file.