You execute the following block of code：  
SQL>BEGIN  
DBMS_RESOURCE_MANAGER.CREATE_SIMPLE_PLAN  
（ SIMPLE_PLAN => ’DEPARTMENTS’，  
CONSUMER_GROUP1 => ’PAYROLLL’，  
GROUP1_CPU => 50，  
CONSUMER_GROUP2 => ’SALES’，  
GROUP2_CPU => 25，  
CONSUMER_GROUP3 => ’MARKETING’，  
GROUP3_CPU => 25）；  
END；  
SQL>/  
What is a prerequisite for using the simple resource plan created by executing the above code？（）