The definition of done (DoD) is a clear and concise list of requirements that a deliverable must meet to be considered complete and acceptable by the main stakeholder. The DoD helps to ensure that the quality standards are met and that the deliverables are aligned with the stakeholder's expectations. The project manager should reinforce the DoD during sprint planning so that the team has a common understanding of what needs to be done and how to do it. This will help to prevent the deliverables from being rejected during the next iteration. Submitting a change request to prioritize resolutions for the quality issue (option A) may be necessary, but it does not address the root cause of the problem, which is the lack of clarity and agreement on the DoD. Assuring that the product backlog is properly prioritized to avoid dependencies that cause rejection (option C) is a good practice, but it does not ensure that the deliverables will meet the quality specifications.
Creating a dedicated sprint to complete all of the pending specifications from previous sprints (option D) may be a viable option, but it may also delay the project and increase the cost. The best option is to reinforce the DoD and ensure that the team delivers what the stakeholder expects. References:
* PMBOK Guide, 6th edition, page 176, section 5.4.2.1 Definition of Done
* [Agile Practice Guide], page 54, section 4.2.2.1 Definition of Done
* PMP Exam Prep, 10th edition, page 425, question 425, answer and explanation