Explanation
According to the Project Management Professional (PMP) Reference Materials, the project manager should request additional resources to be incorporated to the project team when a few key team members recently left the project team, and the remaining members took time to understand the details and found it difficult to make progress, resulting in a serious delay in the project schedule. This is because the project manager needs to ensure that the project has sufficient resources to complete the work within the agreed time, cost, and quality constraints. By requesting additional resources, the project manager can fill the gaps left by the departed team members, and provide the necessary skills, expertise, and experience to the project. The project manager can also use the additional resources to accelerate the work, reduce the learning curve, and mitigate the risks associated with the team turnover. Requesting additional resources can help the project manager to recover from the setback, and deliver the project successfully. References: Project Management Professional (PMP) Exam Content Outline, A Guide to the Project Management Body of Knowledge (PMBOK Guide) - Seventh Edition, How To Handle A Key Team Member Leaving At A Critical Project Point.