Explanation
The project manager should accept only those changes that are approved by the CCB prior to being implemented because this is the best way to control the scope and prevent scope creep. Scope creep is the uncontrolled expansion of the project scope due to the addition of new requirements or changes without proper authorization, analysis, or documentation. Scope creep can negatively affect the project performance, quality, schedule, cost, and stakeholder satisfaction. To control the scope, the project manager should follow the change management process, which includes submitting change requests, evaluating the impact of changes, obtaining approval from the CCB, and updating the project documents and baselines accordingly. The CCB is a group of stakeholders who are responsible for reviewing, approving, rejecting, or deferring change requests based on predefined criteria and authority levels. By following this process, the project manager can ensure that only valid and necessary changes are implemented, and that the project scope is aligned with the project objectives and stakeholder expectations. References:
A Guide to the Project Management Body of Knowledge (PMBOK Guide) - Seventh Edition, Chapter
2.2.3, page 27
PMP Exam Content Outline, Domain III: Executing, Task 8

Section: Closing

Model E: Total cost = 600*4*12 = 28800. PM cost = 28800/48 = 600. Model G: Total Cost = 20000 + 1000*4 + 550*48/10 = 26640. PM Cost = 26640/48 = 555, i.e., approximately $550. Answer is A.