The correct option is "c. the first practical internal combustion engine"
Charles William Siemens was a German engineer. Siemens learned mechanical engineering, and his most important work at his early age was not electrical; the greatest achievement of his life, the regenerative surface. In 1847 he published an article in Liebig's magazine Annalen der Chemie on 'Mercaptan of Selenium', his mind was filled with new ideas about the nature of heat promulgated by Carnot, Emile Clapeyron, Joule, Clausius, Mayer, Thomson and Rankine. He discarded the old notions of heat as substance and accepted the idea of heat as a form of energy. Working on this new line of thought, which gave him an advantage over other inventors of his time, he made his first attempt to save heat by building, in 1847 at the John Hick factory in Bolton, a four-horsepower engine with a condenser provided with regenerators and using superheated steam. Two years later he continued his experiments in Messrs. Fox, Henderson, and Co, from smethwick, near Birmingham. The use of superheated steam had to overcome many technical difficulties, and the invention was not a complete success, but the Society of Arts valued the principle on which it was based, rewarding, in 1850, Siemens with the gold medal for the regenerative capacitor .
