Explanation
= This answer is based on the agile principle of delivering value early and often, which means that the project team should prioritize the features and functionalities that are most valuable to the customer and deliver them in small increments throughout the project. By doing so, the project team can avoid the risk of spending too much time and resources on the final 10% of the project, which may not be as important or relevant to the customer as the earlier deliverables. This approach will also enable the project team to obtain frequent feedback from the customer and make adjustments as needed, ratherthan waiting until the end of the project to validate the results. References: (Project Management Professional (PMP) Reference Materials source and documents) A Guide to the Project Management Body of Knowledge (PMBOK Guide) - Seventh Edition, Chapter
14: Enabling Change, Section 14.1: Planning for Change, page 325.
Agile Practice Guide, Chapter 2: An Introduction to Agile, Section 2.2: Agile Manifesto and Principles, page 11.