According to the PMBOK® Guide, Progressive Elaboration is a fundamental characteristic of projects that integrates the concepts of temporary and unique.

Definition: It is the process of continuously improving and detailing a plan as more detailed information and more accurate estimates become available. It allows a project management team to define work and manage it to a greater level of detail as the project evolves.

Mechanism: In the early stages of a project, the project scope is defined broadly. As the project team better understands the objectives and the deliverables, the specific requirements and work packages are " elaborated " or broken down further. This is most commonly seen in the development of the WBS and Rolling Wave Planning.

Distinction from Scope Creep: It is important to distinguish progressive elaboration from " Scope Creep " (Option A). Progressive Elaboration is a planned, systematic refinement of the existing scope, whereas Scope Creep is the uncontrolled expansion of project scope without adjustments to time, cost, and resources.

Analysis of Other Options:

A. Changing project specifications continuously: This describes " Scope Creep " or lack of change control, which is a negative project state.

B. Elaborate tracking of the project progress: This refers to " Monitoring and Controlling " activities, such as using Earned Value Management, but is not progressive elaboration.

C. Elaborate tracking of the project specifications with a change control system: This describes " Configuration Management " or " Change Control, " which manages changes to the baseline rather than the natural refinement of project details.