According to the PMBOK® Guide, the process of Plan Risk Management—and the overall management of risks—is not a one-time event during the planning phase. Instead, it is a process that is performed periodically throughout the project as needed.

Continuous Nature of Risk: Risks are dynamic. New risks may emerge, and existing risks may change or disappear as the project progresses through different phases. Therefore, the approach to managing risk must be revisited to ensure it remains appropriate for the project ' s current context.

Process Frequency: While many planning processes are primarily focused at the start of a phase, the PMI framework explicitly identifies Risk Management processes as being iterative. The Plan Risk Management process defines how risk management activities will be structured and performed; as the project ' s complexity or stakeholder risk appetite changes, this plan may need adjustment.

Integration with Project Life Cycle: During phase transitions or after significant changes (such as a major scope change), the project manager must re-evaluate the risk management framework to ensure it is still robust enough to protect the project’s objectives.

Why other options are incorrect:

Option B: Plan Communications Management: This process is primarily performed at predefined points in the project (usually at the beginning or during phase starts). While it is updated if communication needs change, it is not characterized in the PMBOK® Guide as a process performed " periodically as needed " in the same iterative sense as risk management.

Option C: Plan Resource Management: Similar to communications, resource planning is typically focused at the start of the project or phase to establish the " how-to " for acquiring and managing the team.

Option D: Plan Cost Management: This is a foundational planning process performed at a discrete point early in the project to establish the policies for estimating, budgeting, and controlling costs. It is rarely revisited " periodically " unless there is a fundamental shift in the organization ' s financial policies or a total project re-baselining.