In the practice of variolation, what was introduced into the body to confer immunity against smallpox?

• A. Purified antibodies against smallpox
• B. Attenuated cowpox virus
• C. Material from smallpox sores
• D. Heat-killed smallpox virus

Answer: (C)

Verified step by step guidance

1. Understand the historical context of variolation, which was an early method used to induce immunity against smallpox before the development of the modern vaccine.
2. Recall that variolation involved introducing material from an infected individual into a healthy person to stimulate an immune response.
3. Identify the type of material used in variolation: it was not purified antibodies, attenuated viruses, or heat-killed viruses, but rather live material taken directly from smallpox sores.
4. Recognize that this material contained live smallpox virus particles, which caused a mild infection that conferred immunity against future smallpox infections.
5. Conclude that the correct answer is 'Material from smallpox sores' because this was the substance introduced into the body during variolation to confer immunity.