According to the Agile Practice Guide, the definition of done (DoD) is a clear and concise list of requirements that a deliverable must adhere to for the team to consider it complete. The DoD helps to ensure that the quality standards and customer expectations are met, and that there is a consistent understanding of what done means among the team and the customer. Therefore, the project manager should have included all relevant criteria in the agreed upon DoD, and crafted a shared product vision that aligns with the customer's needs and goals.
This would have helped to prevent the customer from rejecting the deliverables at the end of the iteration.
Involved the customer more in the planning process for the project, and ensured agreement on the proceedings may be a good practice, but it is not the best answer. The customer may still reject the deliverables if the planning process does not result in a clear and agreed upon DoD and product vision. Provided the customer with the backlog and the specified user stories at the beginning of the iteration may be helpful, but it is not sufficient to prevent the customer from rejecting the deliverables. The backlog and the user stories may change during the iteration, and they may not reflect the quality criteria and the customer expectations. Developed the DoD in close cooperation with all stakeholders to ensure their expectations were included may be a good practice, but it is not the best answer. The DoD should be developed with the customer, not with all stakeholders. Some stakeholders may have different or conflicting expectations than the customer, and they may not be the ones who accept or reject the deliverables. References: Agile Practice Guide, Chapter 3, Section 3.2.2 (Definition of Done) and Section 3.2.3 (Product Vision)