Develop a preliminary WBS for a small one-story commercial building to be constructed on the site of an existing small-frame structure.It is 30 by 60 feet in plan (see illustration). The exterior and interior walls are of concrete block.The roof is constructed of bar joists covered with a steel roof deck, rigid insulation, and built-up roofing. The ceiling is suspended acoustical tile. The floor is a concrete slab on grade with an asphalt tile finish. Interior finish on all walls is paint. A. [15 Pts.] Show the first level of this structure for the total project (WBS is developed from top to the bottom). B. [15 Pts.] Select one work package (or building system) of the first level and develop the second-level structure for this work package.