Final answer:
The answer to the question is a work package, which is a key element in project management used for monitoring and controlling a project at its most granular level.
Step-by-step explanation:
The student has asked about a component of the Work Breakdown Structure (WBS) in project management. Specifically, the deliverable at the lowest level of the WBS that project managers use for monitoring and controlling the project is known as a work package. The correct answer to the question is:
A work package is a deliverable at the lowest level of the WBS that represents the level of work that the project manager uses to monitor and control the project.
Work packages form the foundation of the WBS, providing clear delineation of efforts required to achieve project milestones and deliverables. They allow project managers to break down the project activities into manageable sections, assign responsibilities, and track the progress of the project.