Within a resource-plan definition， what differentiates a top-level plan from a subplan？（）  

• A、 A subplan has the PLAN_SUB parameter value set to SUB
• B、 A top-level plan has the GROUP_OR_PLAN parameter set to the name of the subplan in the resource-plan definition
• C、 There is no difference in the resource-plan definition
• D、 A subplan always has the CPU_MTH parameter value set to RATIO
• E、 The string TOP_LEVEL is appended to the name of top-level resource plans