Which evidence from the text best supports the claim "although many people worked to fight smallpox, Jenner has been given credit for starting and spreading the practice of immunization"? "In 1757, an 8-year-old boy was inoculated with smallpox in Gloucester." "Gradually, vaccination replaced variolation, which became prohibited in England in 1840." "On May 14, 1796, using matter from Nelms' lesions, he inoculated an 8-year-old boy." "Jenner sent vaccine to his medical acquaintances and to anyone else who requested it."

"Jenner sent vaccine to his medical acquaintances and to anyone else who requested it."

Explanation:

The history and treatment of smallpox disease are one of the most devastating diseases to affect mankind. Edward Jenner's achievements and vaccination development helped us lead a life free of such a devastating disease.

The claim that while there were many people who worked hard to get a vaccine for the disease is best supported by the evidence that "Jenner sent vaccine to his medical acquainted and to anyone else who requested it". His efforts in discovering the vaccine and then sending it to anyone who needs it was what helped him become more known as the one who started the practice of immunization. Many people had worked on ways to cure the disease even before Jenner, but it was he who discovered and spread the immunization practice.

Thus, the correct answer is the last option.