Many of the activities performed during the preliminary investigation are still being conducted in ____, but in much greater depth than before. During this phase, the analyst must become fully aware of the ____ and must develop enough knowledge about the ____ and the existing systems to enable an effective solution to be proposed and implementeD．Besides the ____ for process and data of current system, the deliverable from this phase also includes the __请作答该选项__ for the proposed system.
A.hardware anD.software specification
B.system performance specification
C.formal requirements definition
D.general problem statement