I believe that the answer is D, because they used a lot of libraries because of scholars.
The Bessemer process<span> was the first inexpensive industrial </span>process<span> for the mass production of steel from molten pig iron before the development of the open hearth furnace. Therefore, the answer your looking for would be steel. :)</span>
Belgium, Britain, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal for US and Bulgaria, Czechoslovakia, the German Democratic Republic (East Germany), Hungary, Poland and Romania for Russia
