what of the following revolutionized the steel industry?
a. the bessemer process
b. the switchboard
c. the mail-order catalog
d. the bell company

The answer would be option A "the Bessemer Process." The Bessemer Process was the first inexpensive process to help production of steel and iron before further revolutionizing inventions. The impact of the Bessemer Process was beyond imaginable and it changed the steel industry and a very big way. The Bessemer Process was created back in 1856.

Hope this helps.

napoleon the third became a empire in 1873 also known as the era of the franco-prussian war.