The correct option is A Henry Becquerel
Radioactivity means ray emitting activity, this phenomenon of radioactivity was discovered in 1896 by Professor Henry Becquerel, when he was working on the nature of phosphorescent substances. He found that Uranium salt emitted invisible radiations that affected a photographic plate, it penetrated through a metal sheet, and remained unaffected by changes in temperature and was later called as a radioactive element.