Which person would have been MOST grateful for the work of 19th century scientist Edward Jenner? A) someone attempting to fly B) someone harvesting cotton C) someone diagnosed with smallpox D) someone trying to look at blood cells

The correct answer is option C: someone diagnosed with smallpox.

The person that would have been most grateful for the work of 19th-century scientist Edward Jenner, would be someone diagnosed with smallpox because Jenner was who discovered the first vaccine against the smallpox virus. Moreover, this disease that was widely spread in the 18th century and killed many people.