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 （71）. It determines how the various results are computed by the product and presents this information in the form of a （72） and associated scenarios. The second is （73） , which determines the classes and their attributes, then determines the interrelationships and interaction among the classes. The last step is （74） , which determines the actions performed by or to each class or subclass and presents this information in the form of （75）.

（72）处填（）。

A．collaboration diagram

B．sequence diagram

C．use-case diagram

D．activity diagram