Answer:
He discovered penicillin, which solved several problems people suffered from infections.
Step-by-step explanation:
Alexander Fleming was a Scottish scientist, doctor and bacteriologist. He is recognized for the discovery of penicillin, considered one of the most important for humanity. Through it, thousands of people have been cured of infections that could lead to death. Penicillin is currently the most widely used antibiotic in the world.
Despite acknowledgment of his discovery, Fleming stated the following sentence: "I didn't invent penicillin. Nature did it. I just discovered it by chance."