D. His method for producing steel in large quantities allowed it to be used on a massive scale.
Explanation:
Sir Charles William Siemens built up his regenerative furnace during the 1850s, for which he asserted in 1857 to ready to recuperate enough warmth to spare 70–80% of the fuel. The furnace worked at a high temperature by utilizing regenerative preheating of fuel and air for combustion. Through this strategy, an open-hearth furnace can achieve temperatures sufficiently high to melt steel.
