Identify a contribution of Antonio Sant'Elia as an architect.
a. He produced visionary projects with multiple levels of exposed horizontal circulation and prominent power-production facilities.
b. He designed the Einstein Tower using the graphic technique of Erich Mendelsohn's sketches.
c. He designed the Monument to the Third International (Communist Congress) in 1919.
d. He built rhomboidal volumes and cantilevered structures that emphasized dynamism and the agenda of Soviet Communism.