What structure decomposes project scope into phases, work packages, and deliverables?

The Work Breakdown Structure (WBS) is the correct answer because it is specifically designed to decompose project scope into manageable sections, which include phases, work packages, and deliverables. The WBS breaks down the entirety of a project into smaller components, enabling better scope management, resource allocation, and risk assessment. This hierarchical structure allows project managers and stakeholders to understand the project's complexity, track progress, and ensure that all necessary tasks are completed efficiently.

In contrast, the project timeline structure focuses on scheduling and the sequence of tasks over time. The resource allocation structure deals with assigning resources to different parts of the project rather than breaking down the scope. A goal hierarchy structure is primarily concerned with arranging goals and objectives but does not provide the same detailed breakdown of project scope as the WBS does.