Project risks should be closed when the stakeholders agree a risk is no longer applicable. This ensures that risks are actively managed and only relevant risks are considered throughout the project lifecycle.

According to the PMI Risk Management Professional (PMI-RMP) Reference Materials, project risks are uncertain events or conditions that may have a positive or negative effect on one or more project objectives1. Project risks can be closed when they are no longer applicable to the project or its activities. The process of closing project risks involves verifying that the risk responses have been completed, documenting the outcomes, and evaluating the effectiveness of the risk management process2. The decision to close a project risk should be made by the stakeholders who are responsible for or affected by the risk, as they are the ones who can determine whether the risk is still relevant or not. Therefore, the correct answer is B. When the stakeholders agree a risk is no longer applicable.