Which of the following is used to provide a functional description of the efforts which are required in order to accomplish a task?

A Gantt chart is a bar chart used for scheduling project tasks over time, showing start and end dates, but it does not provide functional descriptions of effort.

PERT (Program Evaluation and Review Technique) is a method used for estimating project activity durations, particularly in projects with uncertain activity times, not for functional descriptions of efforts.

GERT (Graphical Evaluation and Review Technique) is a network analysis technique that allows for conditional branches and loops, more complex than PERT, but still focused on modeling project flow and duration, not functional descriptions.

A WBS dictionary is a document that provides a detailed functional description of each component of the Work Breakdown Structure (WBS), including the work package description, assigned organization, schedule milestones, and resources needed. It clarifies the scope and effort required for each element of the WBS.