According to the PMBOK® Guide, specifically the Perform Integrated Change Control process, any change that impacts the core parameters of the project (Scope, Schedule, or Cost) requires a formal update to the project ' s baselines.
Project Baseline (Choice B): A baseline is the approved version of a work product that can be changed only through formal change control procedures and is used as a basis for comparison to actual results. The Project Management Plan contains three primary baselines: the Scope Baseline, Schedule Baseline, and Cost Baseline. When a change request is approved, these baselines are updated to reflect the new approved reality against which performance will be measured.
Project Charter (Choice A): The Project Charter is a high-level document issued by the project initiator or sponsor that formally authorizes the project. It is not a component of the Project Management Plan. While it can be amended if the project’s business objective changes fundamentally, it is not updated through the standard project change control process used for plan components.
Assumption Log (Choice C): While the Assumption Log is a project document that may be updated as a result of a change, it is not a " component of the project management plan. " PMI distinguishes between the Project Management Plan (which contains baselines and subsidiary plans) and Project Documents (like the Assumption Log, Issue Log, and Risk Register).
Schedule Forecast (Choice D): A schedule forecast is an estimate or prediction of conditions and events in the project’s future based on information and knowledge available at the time of the forecast. It is an output of the Control Schedule process, not a constituent component of the management plan itself.
In summary, the Project Management Plan is the master document used to manage the project. When a change is approved via the Change Control Board (CCB), the Project Baseline is the specific component within that plan that must be revised to maintain an accurate measurement for project performance.