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？（）
- A You must assign users to consumer groups.
- B You must grant the switch privilege to the users.
- C You must create a resource plan directive.
- D You must specify the complex resource plan.