The German and the name of the guy is Fritz Haber.
It was the refinement of the Bessemer process, first used in the United States in the 1860s, that allowed for the major advance in skyscraper construction. As steel is stronger and lighter in weight than iron, the use of a steel frame made possible the construction of truly tall buildings.
B. <span>a shield of missiles over the U.S. designed to shoot down incoming nuclear missiles from the USSR</span>
