What concept did Pasteur demonstrate using the chicken cholera experiment?

• A. Vaccination
• B. Immunization
• C. Attenuation
• D. Fermentation

Answer: (C)

Attenuation is demonstrated here. Pasteur showed that a pathogen can be weakened so it no longer causes disease but can still train the immune system to recognize and defend against it. He observed that older, less virulent cultures of the cholera bacterium could infect chickens without making them sick, and when those chickens were later exposed to the virulent form, they were protected. This is the idea behind using attenuated pathogens as vaccines: a safe, weakened form prompts immunity without causing illness. It’s not about the act of administering a vaccine or the state of being immune itself, and it isn’t about fermentation, which is a different process Pasteur studied.