A company has contracted with an external consulting firm to implement a commercial financial system to replace its existing system developed in-house. In reviewing the proposed development approach, which of the following would be of GREATEST concern? 
A、Acceptance testing is to be managed by users. 
B、A quality plan is not part of the contracted deliverables. 
C、Not all business functions will be available on initial implementation. 
D、Prototyping is being used to confirm that the system meets business requirements.