What is the lowest level in the WBS at which the cost and activity durations for the work can be reliably estimated and managed?

A.
Work Product

B.
Work Package

C.
Project deliverable

D.
Scope Baseline

Explanation:
A work package is a portion of the work breakdown structure that allows project management to define the steps necessary for completion of the work package. A work package can be thought of as a mini project, that when combined with other work package units, form the completed project. An individual work package contains essential steps involved in completion of the work package along with a deadline by which each of the steps must be completed in order for project management to stay on track. A work package may in itself be thought of as a deliverable. Work packages allow for simultaneous work on many different components of a project at the same time by multiple teams. Each team follows the steps defined in the work package and completes them by the specified deadline. When all teams have finished their individual work packages, the whole project comes together with seamless integration. Completion of a work package is most often overseen by a specific person whether it is a manager, supervisor, team leader, or a designated team member. A work package is usually the bottom tier of the project management process. Related term: control account.