What Must Take Place to Ensure the Success of a CRM

What must take place to ensure the success of a CRM system?

A) salesperson cooperation through a clear set of incentives and direct benefits associated with use of the system
B) complete control of the system by the marketing department
C) limited access to the system by people outside of sales (customer support, IT personnel, etc.)
D) hiring an outside company to input and maintain relevant data into the system
E) customer willingness to participate in the system