When a risk that has been previously identified occurs, the project manager should consult the risk register to determine the planned responses for this risk event. The risk register contains the details of risk responses that are planned for the identified risks, including contingency plans and fallback plans. Implementing the planned risk response is crucial to manage the risk effectively and keep the project on track. This approach is aligned with the PMI's guidelines on risk management, which emphasize the importance of preparing for and responding to risks proactively. References: (Project Management Professional (PMP) Reference Materials source and documents; Professional in Business Analysis Reference Materials source and documents)