Answer: The correct answer is : Louis Sullivan used the second section of the skyscrapers for the Offices. A skyscraper is used to save space and for commercial uses as it is high instead of broad saving land space and using sky space. Sullivan's theory of tall buildings included a tripartite (three-part) composition: Base, Shaft and Attic based on the structure of the classical column, and his desire to emphasize the height of the building, with the second floor filled with easily accessible public offices A cornice separates the second floor from the grid of identical windows of the screen wall, where each window is like a cell in a honeycomb.
