The Eads Bridge, which crosses the Mississippi River near St Louis, Missouri, was one of the first all steel bridges built in the world. The bridge was built by the Keystone Bridge Co. pany, and, during development, engineers decided that all-steel would be the best construction, even though it was more expensive, because it would have the greatest strength, which was needed due to the beidge's size. This description of engineering can be classified as __ A.) Neither a case study nor case history
B.) A case history
C.) A case study
D.) Both a case study and a case history.