Which of the following levels of the work breakdown structure (WBS) includes an explanation of...

The correct answer is A. Project . The CSSBB material explains that the work breakdown structure (WBS) expands the project or statement of work into a detailed listing of activities required to complete the work. This means the highest level of the WBS is the project itself , and that top level carries the overall objective, scope, and purpose. Lower levels such as phases, activities, and tasks are breakdown elements used to organize and execute the work, but they do not define the fundamental purpose of the project.

The CSSBB source also describes a project as a series of activities and tasks with a specified objective , along with starting and ending dates and necessary resources. That objective is what explains the reason or purpose for the effort. Once the project is defined, the WBS decomposes it into smaller pieces for planning and control. Therefore, the explanation of the project’s purpose belongs at the project level , not at the phase, activity, or task level. In Six Sigma project management, this top-level definition aligns with the charter and statement of work, making Project the correct answer.