The material had the oxygen that could help the cells of the body fight off smallpox infection is the best explains the reason that Jenner decided to infect Phipps.
The first successful vaccination was Edward Jenner's smallpox vaccine, which was launched in 1796.
He discovered that milkmaids who had previously contracted cowpox were immune to smallpox, and that injected vaccinia protected against inoculated variola virus.
Thus, option C, The material had oxygen that could help the cells of the body fight off smallpox infection is the reason to infect the Phipps.
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