You work as a database administrator for Supportcenter.cn. 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？（）
- AThe advisory memory has been turned off.
- BThe DB_CACHE_ADVICE parameter has been set to OFF in the parameter file.
- CThe STATISTICS_LEVEL parameter has been set to BASIC in the parameter file.
- DThe TIMED_STATISTICS parameter has been set to FALSE in the parameter file.
- EThe STATISTICS_LEVEL parameter has been set to TYPICAL in the parameter file.