There is more than one way to set the server to detect and affect long running operations automatically. What is the best choice of you want to reduce the impact of long running operations on other users without aborting the long running operations？（）

• A、Define user profiles and set the CPU_PER_CALL limit. 
• B、Define a SWITCH_TIME for a plan in the Resource Manager. 
• C、Create a batch job that checks V$SESSION_LONGOPS；the batch job alters the session priority of the long running operations. 
• D、Create a user defined event in the Oracle Enterprise Manager， which monitors V$SESSION_LONGOPS.