I think the answer is (B. Vocation) [UnSure]
Answer:
steel processing
Explanation:
The economic development of the United States of America in the last third of the 19th and beginning of the 20th century was characterized by a significant acceleration of growth, which allowed the country to take the place of the leading industrial power of the capitalist world. From 1870 to 1900 tons, pig iron production in the country increased 8 times, coal production - 10, steelmaking - 150 times.
In the 1850s, when the Bessemer process was invented in the UK, the American William Kelly developed a similar process for the production of high-grade steel from cast iron, suitable for use in shipbuilding, railways and in the manufacture of weapons. In the years 1868-1872, Andrew Carnegie used the latest inventions for the production of steel in the steel company he created, whose plant was built in Pennsylvania near the junction of several railways.
