(1)analysis emphasizes the drawing of pictorial system models to document and validate both existing and/or proposed systems. Ultimately, the system models become the (2)for designing and constructing an improved system. (3) is such a technique. The emphasis in this technique is process-centered. Systems analysts draw a series of process models called (4).(5) is another such technique that integrates data and process concerns into constructs called objects.
空白（4）处应选择（）
A.PERT
B.DFD
C.ERD
D.UML
