According to the PMBOK Guide, one of the key activities in the closing process group is to ensure that the project or phase information is archived, the planned work is completed, and organizational team resources are released to pursue new endeavors1. Knowledge transfer is an important part of this activity, as it involves sharing the lessons learned, best practices, and project outcomes with relevant stakeholders and other projects. Knowledge transfer helps to improve organizational performance, enhance customer satisfaction, and enable continuous learning2. Therefore, ensuring that knowledge transfer activities are executed as planned should be considered as a priority for the project manager in the closing process group. The other options are not as important or relevant as knowledge transfer. Marking the product backlog completion status and updating the communications management plan are part of the monitoring and controlling process group, not the closing process group1. Releasing the resources and planning for a project completion celebration are also part of the closing process group, but they are not as critical as knowledge transfer for the project success and organizational benefit1. Holding a steering committee meeting to inform them of the project completion is a good practice, but it is not a priority activity, as it can be done after the knowledge transfer is completed3. References: PMBOK Guide, 6th edition, Chapter 4.7, Knowledge Transfer in Project Management - PMI, How to Close a Project - ProjectManager.com