Which invention or innovation produce better iron?
a. using coal to smelt iron
b. using steam engines
c. the bessemer process
d. the putting out system

The correct option is: c. the bessemer process  

The Bessemer process was created and patented in 1855 by Henry Bessemer and was the most economical industrial process designed to manufacture steel from molten pig iron. The process consists of using oxidation to remove impurities from the pig iron by blowing air into the iron .