You want to purge job entries older than 5 days from the job log. You do not want to purge window log entries. Which command will you use to accomplish this task？（）  

• A、 EXECUTE DBMS_SCHEDULER.PURGE_LOG（log_history => 5， job_name => ’JOB1’）；
• B、 EXECUTE DBMS_SCHEDULER.PURGE_LOG（ log_history => 5， job_name => ’JOB_LOG’）；
• C、 EXECUTE DBMS_SCHEDULER.PURGE_LOG（ log_history => 5， which_log => ’JOB1’）；
• D、 EXECUTE DBMS_SCHEDULER.PURGE_LOG（ log_history => 5， which_log =>’JOB_LOG’）；