All of the following estimation principles are associated with typical plan-driven or waterfall estimation process except one. Which one is associated with the typical agile estimation process. which one of the following is associated with the agile estimation process?

A. Limited transparency and visibility of the user to project details and issues

B. Collaborative join partnership model

C. Arm's length contract based on firmly defined and signed off requirements

D. Changes to requirements are controlled and any significant changes are treated as an exceptional situation