How did Florey contribute to the research on penicillin?

Florey's significant contribution to penicillin research revolves around his role in developing it as a practical treatment for bacterial infections. He, along with his colleague Ernst Boris Chain, took the findings of Alexander Fleming, who initially discovered penicillin, and built upon them. While it’s true that Florey and his team found Fleming's work instrumental, his major impact came from their experimental work that demonstrated how penicillin could be used effectively, especially during World War II.

The correct answer highlights Florey's connection to Fleming's earlier research, which laid the groundwork for the systematic study and development of penicillin as a medicine. However, Florey’s leadership in the production and distribution of penicillin for widespread use during the war was crucial, where he facilitated the transition from a laboratory finding to a life-saving drug, addressing the urgent needs posed by infections in soldiers.

The other options reflect different aspects of the history surrounding penicillin but do not accurately capture Florey's key role in advancing its use in medicine. Discovering penicillin was primarily Fleming's achievement, not Florey’s. The mass production efforts were indeed part of Florey's endeavors, but they are not accurately represented in the choice indicating he merely found Fleming's old journals.