The Bessemer process for (converting) iron to steel (was invention) of enormous importance (because) it led to many (significant) changes in industrial processes. A: converting B: was invention C: because D: significant

According to the passage, how did Bessemer method make the mass production of steel possible A: It directed air at melted iron in a furnace, removing all impurities. B: It slowly heated iron ore then stirred it and heated it again. C: It changed iron ore into iron which was a substitute for steel. D: It could quickly find deposits of iron ore under the ground.