A resource breakdown structure is a resource hierarchy. Which of the following is usually used to break it down?资源分解结构是一种资源层级结构,通常按以下哪个来分解? A.
Resource category and quantity资源类别和数量 B.
Resource category and type资源类别和类型 C.
Resource category and usage time     资源类别和使用时间 D.
Resource categories and costs 资源类别和成本