开展专用线共用是为了（）缓解铁路货场能力不足、保证、挖掘专用线潜力，满足国民经济发展的需要。

A、企业发展

B、货位周转

C、运输畅通

D、货场畅通

Object-oriented analysis (OOA) is a semiformal specification technique for the object-oriented paradigm. Object-oriented analysis consists of three steps. The first step is (96) . It determines how the various results are computed by the product and presents this information in the form of a (97) and associated scenarios. The second is (98) , which determines the classes and their attributes, then determines the interrelationships and interaction among the classes. The last step is (99) , which determines the actions performed by or to each class or subclass and presents this information in the form of (100)

A．activity diagram

B．component diagram

C．sequence diagram

D．state diagram