Read this excerpt from "Edward Jenner and the History of Smallpox and Vaccination.” After introducing cowpox inoculation in their own districts, many recipients passed the vaccine on to others. Dr. John Haygarth (of Bath, Somerset) received the vaccine from Edward Jenner in 1800 and sent some of the material to Benjamin Waterhouse, professor of physics at Harvard University. Waterhouse introduced vaccination in New England and then persuaded Thomas Jefferson to try it in Virginia.

PLEASE HELP
Which central claim may be inferred from this excerpt?

Many people attempted to discover a vaccine.
Thomas Jefferson spread the vaccine across the country.
Many people worked together to spread the idea of the vaccine.
Jenner selected specific patients who would benefit from the vaccine.