Progressively elaborating high-level information into detailed plans is performed by the:

According to the PMBOK® Guide (Project Management Body of Knowledge), specifically within the chapters on The Role of the Project Manager and Project Management Processes:

Project Manager (Option D): The project manager is the person assigned by the performing organization to lead the team that is responsible for achieving the project objectives. A core part of this responsibility is progressive elaboration, which involves continuously improving and detailing a plan as more detailed and specific information and more accurate estimates become available. The project manager leads the effort to take high-level information (from the Project Charter) and break it down into the detailed Project Management Plan.

Project Management Office (PMO) (Option A): The PMO is a management structure that standardizes the project-related governance processes. While a PMO may provide the templates or oversight for planning, it is not the entity that performs the day-to-day progressive elaboration of a specific project ' s details.

Portfolio Manager (Option B): Portfolio management focuses on ensuring that projects and programs are aligned with strategic business objectives. They deal with high-level selection and prioritization rather than the detailed elaboration of individual project plans.

Program Manager (Option C): A program manager maintains responsibility for a group of related projects. While they ensure alignment between projects, the granular, progressive elaboration of a specific project’s scope, schedule, and resources is the functional duty of that project ' s assigned manager.

In the PMI framework, Progressive Elaboration allows a project management team to manage to a greater level of detail as the project evolves. It is a key characteristic of the project life cycle, distinguishing the broad initial assumptions from the finalized, actionable execution plans developed by the Project Manager.