Jenner's discovery contributed to vaccination against which disease?

• A. Measles
• B. Polio
• C. Smallpox
• D. Tuberculosis

Answer: (C)

The main idea being tested is how vaccines train the immune system by using a gentler, related organism to protect against a more dangerous disease. Jenner noticed that milkmaids who had caught cowpox seemed immune to smallpox. He took material from a cowpox sore and inoculated a boy, then later exposed him to smallpox. The boy did not develop smallpox, showing that the cowpox infection had trained the body to resist smallpox. This demonstrated a practical way to build immunity and started the whole vaccination approach.

This discovery specifically led to vaccination against smallpox, the disease Jenner targeted. The other diseases—measles, polio, and tuberculosis—got vaccines developed in later years, but Jenner’s work laid the foundational method for protecting against smallpox and sparked the broader concept of vaccination.