A change control system is$?$

a$.$ The processes required to ensure that the project is completed within the approved budget

b$.$ Devising and maintaining a workable scheme to ensure that the project addresses the organization's needs

c$.$ A management review that should occur after each project phase to determine if projects should be continued, redirected, or terminated; also called a kill point

d$.$ A formal, documented process that describes when and how official project documents may be modified, the people authorized to make modifications, and the paperwork required for these changes.