Who developed the polio vaccine in 1953?

• A. Albert Sabin
• B. Francis Crick
• C. Alexander Fleming
• D. Jonas Salk

Answer: (D)

The main idea here is recognizing who led the development of the first effective polio vaccine. Jonas Salk developed the first widely used polio vaccine, an inactivated (killed-virus) version. His work culminated in the early- to mid-1950s era of trials and public introduction, with the vaccine becoming available after the trials and safety results in that period. This achievement dramatically enabled mass immunization and helped reduce polio outbreaks. In contrast, Albert Sabin later developed a different polio vaccine (the oral, live-attenuated version) in the 1960s, while Francis Crick and Alexander Fleming are known for other major scientific breakthroughs (DNA structure and penicillin, respectively). So the figure most closely associated with developing the polio vaccine in that era is Jonas Salk.