Which of the following is NOT one of the four main parts of the Premiere Workspace?

The four main parts of the Premiere Workspace are designed to facilitate different aspects of video editing. These include the Source Monitor, which is used for previewing clips before adding them to the Timeline; the Project Panel, where all media assets of the project are organized; and the Timeline, which is the area where you arrange clips and manipulate the flow of the edits.

The Effects Panel, while essential for applying transitions, visual effects, and other modifications to clips, is not one of the fundamental parts of the workspace structure. It serves more as a supplementary tool that enhances the functionality but does not form the core layout required for the initial stages of editing. Thus, the correct answer identifies the Effects Panel as something that does not belong to the primary components of the Premiere Workspace, focusing instead on those elements that are essential for organizing and executing video edits.