According to the PMBOK® Guide, the Identify Stakeholders process is not a one-time event. It is a process that is performed periodically throughout the project.

Initial Identification: The process typically first occurs as the project is being authorized (when the Project Charter is produced) to identify those who have a vested interest in the project ' s outcome from the start.

Phase Transitions: Stakeholders can change as the project moves from one phase to another (e.g., from design to construction). Therefore, it should be performed at the beginning of each phase.

Dynamic Environment: Significant changes—such as a change in project leadership, a major scope shift, or a change in the organization ' s structure—can introduce new stakeholders or change the influence level of existing ones.

Why other options are incorrect:

Option A: While identifying stakeholders at the beginning of each phase is correct, it is incomplete because it ignores the initial identification during the chartering process and the need to respond to significant changes.

Option B: Only performing this at the beginning is a major risk. New stakeholders may emerge, or the power/interest of existing stakeholders may shift, leading to project delays or lack of support if they are not managed.

Option C: Stakeholder identification is a formal, proactive project management requirement. It should not be reactive or based solely on the project manager ' s personal level of concern.