Henry Bessemer: Identify his landmark metallurgical innovation. Full question: What did Henry Bessemer invent? Choose the correct option.

Given data

• Person: Henry Bessemer.
• Field: Metallurgy/industrial processes.

Concept / Approach
Bessemer introduced the Bessemer process—blowing air through molten iron to oxidize impurities—enabling large-scale, cheaper steel production.

Option notes
Open-hearth is Siemens–Martin; the spinning jenny is James Hargreaves; cotton gin is Eli Whitney.

Final Answer
Bessemer process (converter) for making steel.